British mineralogy or, Coloured figures intended to elucidate the mineralogy of Great Britain, Volume 4

BRITISH MINERALOGY:

OR

COLOURED FIGURES

INTENDED TO ELUCIDATE

THE MINERALOGY

OF

(threat Btttattu

BY JAMES SOWERBY, F.L.S.

HONORARY MEMBER OF THE PHYSICAL SOCIETY OF
GOTTINGEN,

DESIGNER OF ENGLISH BOTANY, AUTHOR OF
ENGLISH FUNGI, ETC.

(With Assistance.)

As for the Earth, out of it ccmeth Bread, and under it is turned up as it
were Fire. The Stones of it are the Places of Sapphire* ; and it hath
Dust of Gold. Job xxviii. 5, 6.

VOL. IV.

LONDON:

PRINTED BY

RICHARD TAYLOR AND CO., SHOE-LANE, FLEET-STREET;

And sold by the Author, J. Sowerby, at No. 2, Mead Place, Lambeth;
and by White and Co., Fleet-street; Sherwood and Co.,
Paternoster-row; and all other Bobksellers,

mdcccxi.

1

TAB. CCCI.

CUPRUM sulphureum.

Sulphuret of Copper ; Swimming Pyrites.

Div. 2. Imitative.

It is now no novelty to find Metals of very light specific
gravity, since Mr. Davy's discovery of Sodium and Potassium,
yet we have no account of Swimming Copper Pyrites, that
I know of. I am therefore glad to treat the world with
this novelty. Some time ago Mr. Came favoured me with
the Swimming Quartz which had some porous Sulphuret
and Oxide of Copper about it, which gave me reason to
suppose some Swimming Copper Ore might be found,
since which time he has kindly informed me that he has
procured a specimen, and I have, by chance, received this
from the same place *.

It would seem from its appearance to have been formed by
passing among the irregular interstices of some shattered
part of a rock which is completely gone in the same manner
as from the Quartz above. It is in somewhat plated
chambers irregularly angular of various dimensions. It is
extremely friable, and the tenuity of the plates or divisions
will scarcely allow of its being handled. It is a kind of
exception to the rule by which we judge of the specific
gravity or weight of Metals by the hand, to distinguish
them from the Combustibles and Earths, and is a food
example of an argument regarding the gravitating principle,

* From Trelistian Mine, near Penzance in Cornwall.
VOL. IV. J3

2

that, under certain circumstances, the Metals may lie above
the Earths and Combustibles, when in a divided state.
Thus it is lighter than water in this porous form, although
its solid specific gravity in comparison to that of Water is
as 4-315 to 1000 : so that, in judging of specific gravity,
the solid state of the substance must be attended to.

s

TAB. CCCII.

CUPRUM hyperoxygenizaturru
Peroxide or Hydrate of Copper.

Biv. 3. Amorphous.

As it is interesting to Geologists to see what substances
come together, I figure this variety of Copper Ore mingled
with the black Oxide of Manganese in the same bed or
part of the vein. It is extremely curious to find it so clean
and bright among the loosely cracking, almost powdery
Manganese which is so liable to soil any thing near it.
Nature, here, however, shows us a striking example of
the inseparable connexion between the particles of certain
substances, so important to defend us from that chaos
which might otherwise ensue.

This is a variety of the same Copper Ore as tabs. 279 and
1280, containing much Silex, and, having most of the different
appearances, as to colour, from nearly white to yellower
and blueish green, probably depending on the quantity of
water it holds. The dark green parts are Carbonate of
Copper.

K 3

fa

INI

M

I

5

TAB. CCCIII.

CUPRUM arseniatum.
Arseniate of Copper.

Class 3. Metals. Order 1. Homogeneous.

Gen, Copper. Spec. Arseniate of.

In addition to our former figures of Arseniate of Copper,
tabs. 168, 169, I/O, I am happy to figure these curious
varieties, not merely because they are rare, but as examples
that are of more consequence, as they will explain many
groups of this substance that are scarcely, if at all, under-
stood. The present rotate specimens, if I may so call
them, are, as it were, a congeries formed of the truncated
triedral column, chiefly like the left hand bottom outline.
The other outline shows, by the small dots, that one of the
solid angles is sometimes replaced by a new face, which
would give it a wedge form, very applicable to the rotate
formation of the upper specimen : they, however, seem
more perfect columns, and are placed among each other
somewhat upon the principle of the Galena in tab. 131.
The middle outline shows the columnar sides and the tri-
angular ends, nearly as they appear when magnified. Some
are very small, and others larger and more irregular, some-
what approaching the broad faces, and even the mackles,
as in the next figure.

6

TAB. CCC1V.

At first sight this looks like a very different modification
from the last. It is, however, only more perfectly accu-
mulated on the periphery of a wheels as it were, united
in large faces, either upon opposite ends of crystals, like
the right hand lower figure, or mackle, and is sometimes
formed of a variety composed of many, partly belonging
to the left hand lot torn figure. The ends become small
and rough around the series of tab. 303, but large and
smooth around this ; whilst, on the contrary, the radii of
the latter or column are generally most confused.

I

(

9

TAB. CCCV.
CALX carbonata.
Crystallized Carbonate of Lime.

Class 2. Earths. Order I. Homogeneous.

Gen. Calx. Spec. Carbonata.

Div, 1. Crystallized. Var. Hexaedral Prisms.

Syn. Chaux carbonatee prismatique. Haily, 2. 141.

The simple hexaedral column is among the scarcer forms
of this substance in Britain.

The present specimens came from Cumberland. Crys-
tals of this form more rarely occur in Derbyshire. In
Scotland they are found at Strontian with Stilbite on the
opposite side of the specimen, as figured at tab. 258. In
some instances the whole form of the crystals is very neat>
and every face is polished.

The upper specimen has not the end face polished, but
roughish.

The lower specimen is most extraordinary, as on it the
crystals have very short columns and lie in various di-
rections, having both ends opaque, but are smooth and
polished on all the faces. The cause of polished faces
might seem to depend upon the gradual separation of the
menstruum or solvent from which it crystallized ; and a
great quantity might, by suddenly passing off, leave the
terminations of the crystals rough as in the upper specimens,
which are not finished at both ends ; tJw lower crystals
probably derive their opacity from a scanty supply of
water of crystallization at the ends.

Some of the crystals in the upper specimen have the ter-
minal edges bevilled towards the column which leads to
other formations — see the next figure,

VOL. IV, c

WE

10

TAB. CCCV1.

CALX carbonata^
Carbonate of Lime.

Class 2. Earths
Gen. Calx

Order 1. Homogeneous.
Spec. Carbonata.
Div. 1. Crystallized. Vau

The present modification is far from common, and has
so peculiar an appearance that it must attract the obser-
vation of the enlightened enquirer, showing how infi-
nitely various may be the modifications of this substance.
The edges of the three sides of the column are rounded
by repeated facets on that and on the pyramid, and the
other three sides of the column are bevilled laterally to-
wards the former three, making with them and the pyra-
mid a figure like the front of a Gothic arch. The thick-
ness of the column, and depth in the proportions of the
flatter, or rounding, facets, give this a variable appear-
ance. The pyramidal ends are often distinct, and nearly
correspond with the primitive rhomb.

1

i

^April t iSoc) JTuMiiftd by Ja* Scwerby Zendcn

11

TAB. CCCVII.

S I L E X Quartzum, var.
Octaedral Calcedony.

Class 2. Earths. Order I. Homogeneous,
Gen. 4. Silex. Spec. Quartzum.

Div.2. Imitative. Far. Octaedral.

Syn. Quartz Agathe. Ilcd'iy, 2. 424.

I was favoured with this fme specimen by Lord Heath-
field, who sent it from Beer Alstone in Devonshire. It is
a secondary crystallization, having taken the form of some
other substance that was prior to it. It has here taken the
place of Fluor or Galcena, most probably Fluor somewhat
like that of tab. 26\ Some of the casts are extremely neat,
others are somewhat hollow, and have Quartz crystals
within them.

c 2

12

TAB. CCCVIII.

Cubic Calcedony.

■ I lilT l n

This is commonly called Cubic Hornstone, but is truly
a Calcedony, as indeed are many things which are com-
monly called Hornstone, and it is hard to show their di-
stinguishing characters. This specimen came from Beer
Aistone, where the curious Octaedral Fluor is found on
what is also called Hornstone — see tab. 26. The crystals are
generally blunt edged, their solid angles truncated, and their
surfaces minutely mamillated, which helps to distinguish
them. This secondary crystallization almost exclusively
belongs to this substance, although there are one or two
instances of its being found in other substances, as in
Steatite, but which is chiefly in the form of Quartz. All
are scarce.

The name Hornstone I suppose to be taken from the re-
semblance the stone bears to horn; a great varietyof stones
have occasionally had that appellation given to them, which
probably vary much in their ingredients, as some little
mixture may help their appearance : thus we might possibly
find Lime, Fluor, and Clay Hornstones.

308,

April i / .VY/> rvbl'uhd bit Jit* Sow srhi> Z^nioH

13

TAB. CCCIX.

S I L E X Quartzum, var. Stalactites,
Stalactitical Calcedony.

Div. 2. Imitative. Var, Stalactitical.

Syn. Quartz Agathe. Hauy, 2. 424.

Tkevascus in Cornwall has afforded the Finest example*
of this peculiar Stalactitical Calcedony. My liberal friends
the Hon. Charles Greville, Philip Rashleigh, Esq. and
Mr. Richard Phillips can show truly magnificent spe-
cimens, above a foot in diameter in some parts, and of
every varied form, including the following examples.

The upper figure serves to express the more usual stalac-
titical formation, and the somewhat undulating rnamillated
appearance common to Calcedony, Resides the blunt,
heavy, and inosculating varieties.

The lower figures show what is commonly called Bony
Calcedony, and have some of the usual appearances ac-
companied by the more unusual ones of slender thready
plates, forming the foraminous appearances which dis-
cover to us something more than what is merely stalacti-
tical, and peculiar to the substance itself; probably de-
pending on the nature of the solution, like most Flints
and flinty substances ; but it never crystallizes as they
do, having that appearance only because it has been
cast into the places where crystals have been.

14

TAB. CCCX.

S I L E X Quartzum, var.
Shell-formed Calcedony.

Diu. 2. Imitative. Far. Shell-like.

I am obliged to the generosity of Mr. Milne of Fonthill
for this specimen. That place and the neighbourhood often
afford Cornua Ammonis of very extraordinary dimensions.
I was told of one that was at Tisbury nearly as big as the
large wheel of a coach. I have one of 21 inches in diameter,
and my friend Mr. W. Cunnington has one larger. They
are often of Sandy Limestone, or limestone with crystals
within, and .now and then there are found the remains of
similar shells in Flint with the chambered divisions partly
calcedonized, if I may use the expression, and containing
Quartz crystals; but the most curious specimen ever seen
is the present^ except one as nearly like it as possible,
which I am told is in the possession of Sir Edward Hulse
of Salisbury. It is perhaps as extraordinary a geological
specimen as any that have been seen. The mass is
chiefly Flint ; but the shell has been lined, and having sub-
sequently decayed, left the Calcedony of the most delicate
and exquisite structure. The peculiarly regular folding
manner of the divisions, and their uniformity, are no where
disturbed. The Calcedony is placed distinctly around
where the shell originally was. There are other minute
shells about the specimen, and also some Carbonate of
Lime, both crystallized and amorphous.

The lower figure exhibits one of the partitions, showing
the tube which passes round the shell, different from what
is usual, as not being a continued channel, but divided into
short tubes, each of which communicates by its openings
with two chambers.

Geologists, as they contemplate the changes which have
here taken place, may well join with David, Linneus, and
all true philosophers, in exclaiming, " Oh ! Jehovah,
great and manifold are thy works ; in wisdom hast thou
made them all ; the Earth is full of thy riches/'

Sir H. C. EngJeficld showed me a beautiful specimen of a
spiral shell with the end passing from Calcedony to Opal,

m

15

TAB. CCCXL

STRONTIA sulphata.

Stellated or radiated Sulphate of Strontian.

Div. 2. Imitative.

This elegant variety of Sulphate of Strontian was found in
sinking a foundation for buildings at Bristol. I do not
know that such has been met with elsewhere. Besides
these stellated ones, there were many very beautifully spicu-
lated. The noble appearance of this, relieved so conspi-
cuously, being formed over Metastatic Carbonate of Lime,
enhances its curiosity. The stellse or radii so much repre-
sent those in general executed by sculptors, that we might
imagine they had had some such an original to imitate ;
and as, I believe, they borrow from antiquity, so I should
imagine the antique models are borrowed from something
in Nature, which indicates that the ancients were not only
capable of taking a proper advantage of what was useful or
instructive to them, but that they probably paid much at-
tention to such subjects, and were not at a loss for originals
to facilitate their study, and help their inventions.

This substance is described at tab. 1 1 7, and in form
much resembles the Lcpastrum or Steljated Sulphate of
Barytes — see tal. 173.

16

TAB. CCCXIL

STRONTIA sulphata.
Brush-like Sulphate of Strontiatu

Brush Iron Ore is spoken of in many authors, but I da
not know of any mention having been made of Sulphate of
Strontian in that form. The specimen here figured, how-
ever, is so perfectly described by that appellation, that very
few will not assent to it. It came from the same place
as the last, and is formed altogether of smaller spicule.
The bundled and, sometimes, twisted elongated arrange-
ment admits of not only a picturesque effect, but exhibits
the pleasing graceful line of beauty so universally attractive
in Nature, that, ever since our Hogarth observed it, we may
be said to have been indulged with a new sense for abstract
beauty.

j

1

?1J

I

17

TAB. CCCXIII.

CARBON vegeto-bituminosus.
Vegetable Coal.

Class l. Combustibles. Order 2. Compound.

Gen. 5. Carbon. Spec. 2. Combined with bi-

tumen and a small portion
of vegetable matter.

Dlv. 2. Amorphous.
Syn. Bituminous Schistus. Hatchett in Linn. Trans,
4. 136.

Kimmeridge Coal, as spoken of by Mineralogists, is ne-
vertheless not very generally known, nor would the sub-
stance, if found in any other place, from its aspect, be
suspected as a Coal, and therefore has been casually over-
looked by those who wanted specimens. It varies some-
what in appearance, as it sometimes divides with a very re-
gular schistose fracture, and it is at other times more
massive and earthy. The same is found a little above the
level of the sea on the eastern side of Portland Island, as
well as at Swanage in Dorsetshire, where it is met with at
the same level. It is used at, Swanage, and in some parts
of Portland, for heating ovens; and although the Bitumen
gives an uncomfortable odour if burned in a common fire,
it does not, I am told, give any effluvia to affect the bread
in the oven.

It may be known by its lightness, and taking an easy
gloss with rubbing the nail over it ; but more particularly

VOL. III. D

18

by its strong blaze in a common fire. It is sometimes sold
for a guinea per ton, and is often in large broad masses,
three or four feet in diameter. It is also sometimes du<r

o

from the rock with a clay shovel.

The upper specimen is somewhat slaty in fracture, though
rather more earthy. It is a softish clayey Shale with much
Petroleum, and emits the smell peculiar to the latter sub-
stance when heated.

The lower specimen is still more earthy, but somewhat
fissile, and is, as it were, interrupted with regard to its
parallels by partly curving round an irregular ball of earthy
Pyrites. It is a curious specimen ; — sometimes Carbonate
of Lime or Chalk intervenes, which is soft. Many other
varieties occur, some of which are more slaty, some more
earthy, and others of different colours.

The Isle of Wight, opposite Alum Bay, affords Bitu-
minous Carbon in great variety. My kind friend Mr. Lyell
favoured me with some that seems to point out the progress
of the Bitumen passing from the vegetables and im-
pregnating the substances near them. Lincolnshire affords
a similar substance, with Lime of shells remaining betwixt
the laminae. I have some sent me by the Rev. R. B. Francis.

A mixture of Bitumen with Lime, Clay, &c. is some-
times found in Essex, nearly resembling this. I have been
favoured with it by Colonel Walford,

19

TAB. CCCX1V.

CALX carbonata, var. metastatica.
Metastatic crystallized Carbonate of Lime.

Div. 1. Crystallized.

This noble specimen of crystallized Carbonate of Lime is
curious, as a variety leading to a kind of Mackle that does
not seem to have been suspected ; but is not rare as to its
formation, for we often see ordinary specimens that partake
of it, having two of the opposite faces of each pyramid
much widened, forming a base to each parallel to the edge
of the primitive nucleus : this will be seen in the next
figure, which maybe compared with tab. 33, the usual Meta-
static Mackle. The two facets, jig. 1, are primitive, and fig. 2
are the same as those of tab. 34, lower figure, equiaxed;
but having those very obtuse-angled faces that so often
produce a rounding form, which help so much in the
numerous varieties of crystals in this substance, and are
extremely curious. Fig. 3 is a somewhat rounded edge
nearly on the angle of the pyramid. The jacets^fig. 4, and
that opposite, are of the hexaedral column. Fig. 5, a facet
nearly on the edge of the nucleus.

The rounded facets in Crystals are sometimes very de-
ceiving; ; and the comparing this with the next plate will
prove the necessity of this leading specimen, which shows
the dividing angle of the natural face of the pyramids
parallel with the primitive edge, that divides the two pn-

D 2

20

mitive facets at 1. I. A little rounding face on the acute
angles of the broader planes of the pyramid towards the fa-
cets of the prism, fig. 4, alters the parallelism of the edges, so
that by turning round the two halves, as in the next figure,
is formed the puzzling appearance so proper to be cleared up,
on account of being totally new in Crystallography, and
extremely curious.

This noble, beautiful, and singular Crystal is from Derby-
shire, and is so suitable to precede the next figure, that I
thought it quite proper to place it here, though indeed it is
only the metastatic formation, as in tab. 35 ; but the
breadth of two of the faces would disguise it to many,
and more so if mackled as in the next figures, with the two
faces still broader, and which this happily serves so clearly
to elucidate, and, by the illinitions of the fractures, helps
to point out the mutual base of the mackling parts ; which
is, I believe, both new and extraordinary, as it coincides
with a plane drawn through the longer diagonal of the
primitive rhomb.

Its colour seems clearly to depend upon the Oxide of
Tron, which is partly mixed and partly chemically com-
bined.

21

TAB. CCCXV.

The present curious production is one of those things
that few can expect to possess; therefore it is, like many
others in this work, a pleasant proof of the utility of figures,
which is certainly next to the possession of the object, as to
the instructive information it gives, and the making public
those beauties of Nature that must otherwise be ever lost
to the scientific world.

I do not know that this formed Crystal has yet been
spoken of: Rome De Lisle and Ilaiiy do not mention it.
It is in the shelly Limestone which forms one of the upper
strata of Derbyshire that this has been formed, hid from
mortal ken, within one of the most remarkable species
of shells I ever knew, Qonchy Holy thus productus of Mr,
Martyn's most ingenious work, plate 22./. 1, 2, 3.

The reason why the primitive molecules should so form,
remains a desideratum. We have but just got a notion of
the subject, but diligence in this discovering age may yet
learn more of Nature's ways, and even this may be the
leading cause: the equally contrariwise attraction of the
particles may be governed by the equal evaporation of the
fluid in contrary directions, and the gravitation of the sol-
vent medium may poise them to that angle which so nicely
replaces them.

One great curiosity of this Mackle is, that the lateral notch

22

at the junction of the two halves at the upper end of the
column is very deceiving, being formed from somewhat
rounding facets, often scarcely discernible, but by these
means become more conspicuous — see the last description.

This specimen was lent me by my friend Mr. Lowrv,
who met with it last summer, and first discovered this
remarkable Mackle.

It is prettily placed in the hollow of the shell among
the Limestone, which has on the left hand somewhat en-
veloped the mineral pith, and crystallized about the bub-
bles.

23

TAB. CCCXVI.

C A L X earbonata, var.
Carbonate of Lime.

Div. 1. Crystallized.
Syn. Chaux carb. analogique. Haiiy, 2. 252.

Common things are often esteemed by common persons
because they look brilliant, and Quartz and Mundic have
been thus vulgarly called Diamonds ; and Diamonds in
themselves of real value, in rude fragments, without a
proper knowledge, might be cast away as rubbish. It is
so lately that the instructive lessons o£ Nature have been
consulted on the useful and elegant study of Mineralogy,
that those who have taken advantage of this growing know-
ledge only know the benefit of it ; they can appreciate
what is to be esteemed valuable; they enjoy that eminence
that sanctions a due value on what is most explanatory of
true science.

The present specimen is very rare and valuable; it shows
that the attraction that brings two crystals regularly together
is confined to one particular side, and not disposed around
the apex of the nucleus, as in the common Mackles ; and
it is new, as it is connected with the columnar modification ;
for we do not know that the columnar crystals of Car-
bonate of Lime have been mentioned as mackled in any
publication before, except the Count de Bournon's ela-
borate Treatise, plate <24,fig. 38S.

Mr. Hewland, who possesses this crystal, sets an addi-

24

tional value upon it, as it was a favourite of his late uncle
Mr. Forster, and was given him by the late Right Hon.
Charles Greville, in whose collection is the only one known
besides. It was an unfortunate jealousy in Rome de Lisle
that hindered its being published long since in his work as
an extraordinary production. I hope such pitiful jealousy
will no longer .be an obstacle to the elucidation of science.

I

■ I

25

TAB. CCCXV1I.

C A L X carbonata
Carbonate of Lime.

Div. 1. Crystallized.

Mineralogical Nomenclators have given titles to crystals
under various circumstances, such as Mackles or Twins ;
and I have exhibited crystals upon crystals which might
have some corresponding or expressive term. The present
is peculiar as to its structure, and is as it were seamed, and
although now perhaps newly noticed, is certainly of as much
consequence as many others, especially as it will furnish
two very instructive and useful examples in Crystallography,
which captivates the fancy so many ways. Here is a
half of the Metastatic* Crystal covered on the three obtuse
angles of the pyramids by a thick coat spreading on either
side, till it meets nearly on the acute angles, forming upon
them a plane with a line or seam in the middle of it, which
makes the modification more conspicuous, at the same
time it is helped by a difference in the inner crystal, which
is somewhat more opaque and whiter than the outer cover-
ing; and in many lights we seethe white reflection between
the two surfaces* The three varied quadrangular faces are
belonging to the common prism of this substance ; those with
the seams form somewhat rounding curved truncations to

* Metastatic means the transposition that happens of the angles of the
nucleus on to the secondary crystal.

'26

the three solid angles of the pyramid ; the terminal faces are
those of the equiaxe and primitive.

The lower is a group of nearly the same nature with the
seams, if I may so call them, more closed, except in
some places where there are small crystals formed, so as to
appear as if bursting out of the cover, on which the py-
ramids rest, or from which they are a continuation.

The lower part of the upper figure has the nucleus very
distinctly in its place, and the diagonal fracture is very
distinct, and serves to show the base of the pyramid. The
Earl of Dartmouth brought me some opaque Limestone
from Lord Dudley's mine with these fractures very distinct.

warn

21

TAB. CCCXVI1L

S J L E X Quartzum, cryst
Crystallized Quartz.

Dlv. 1. Crystallized.

I place this as a most curious example of Quartz new to
the mineralogical writers, the six vertical edges of the co-
lumns of the crystals being truncated, doubling the num-
ber of the faces, as well as those of the pyramid, which
also show the manner of the nuclei accumulating to form
various sportive modifications ; and some of these plates
meeting in seams, as I have called them, tab. 317, di-
stinctly show their nature. Another curiosity attached to
this group is a rotate accumulation of the columnar garnet-
formed Carbonate of Lime, or perhaps Magnesian Pearly
Spar.

Dr. Turton has long deserved my best acknowledgements,
as well as those of the public, not only for his literary ta-
lents in the translation of Limiceus's Sysiema Nature?, but
in his other endeavours to assist in the general knowledge
of Natural History ; nor does he omit to collect specimens
that are useful to those engaged in pourtraying any parti-
cular branch. Among many other kindnesses I am glad
to acknowledge the present most valuable specimen, for its
novelty and very instructive formation. I should think it
were a loss to the public, in a work that is to serve in many
Instances instead of an expensive cabinet, to omit the whole

I

28

specimen, although more really valuable than glaring ; and
besides, a book of crystals merely cannot be so valuable,
and can convey no idea of the specimen it was taken from,
and which it ought to elucidate.

The right hand middle figure shows the Quartz crystal
magnified, and the left hand one shows a crystal detatched
from the group of Garnet-like crystals of Carbonate of
Lime.

The Quartz is extremely rich externally with iridescent
colours 3 but this is lost in smallness.

I

L 1 ^

V

29

TAB. CCCXIX.

STRONTIA sulphata.

Stellated Sulphate of Strontia.

Div. 2. Imitative.

This is rather a geological specimen, and may be useful
as an example of the black rock of Bristol, with the hol-
low showing Carbonate of Lime, Filiate of Lime, and
Sulphate of Strontian, and the rocky mass or gangue is
in this instance of the same formation as that of Derby-
shire, dark Limestone, and like that is a variety of Stink-
stein holding entrochi, shells, &c, as the present spe-
cimen does : it is also analogous to that of Ireland. Having
thought it more essential to figure the substances, that they
may be known first, it may be presumed I need but in a
few instances repeat them in the form of rocks, as the
gangue in many instances, or the whole in some, form
the rocks already, as the Micas and Feldspars in Granite j
the Analcime, &x, in other rocks.

I was favoured with this specimen by Mr. Herbert, a
very ingenious collector, of Bristol.

I:

31

TAB. CCCXX.

S I L E X axinimorphum.

Violet Schorl, or Thinner stone.

Class 2. Earths. Order 1. Homogeneous.

Gen. Silex. Spec. Thumerstone.

Syn. Schorl violet. Jonrn. de Physique, 1785, Janv.
p. 66.

Schorl transparent lenticulaire. De Lisle, 2. 353.
Yanolithe. Lametherie, Sciagr. 1. 287.
La Pierre de Thum, ou Le Thumerstein. Brock.
1. 236.

Thumerstone. Kirw. 1. 273.
Axinite. Haiiy, 3. 22. Karst. p. 22.

I do not know of this substance being found in Great
Britain, excepting in the parish of St. Just in Cornwall.
It is found in many places abroad, as in Siberia, Norway,
Dauphiny, and at Thum in Saxony, whence its name
Tbmnerstein, it having been first discovered at that place.

We find it crystallized in very oblique rhombs — see the
right hand lower figure. Its primitive is a rhomboidal prism,
similar to that of the Sulphate of Barytes — see the left
hand figure. It is mostly of a dull purplish colour, whence
its name Violet Schorl ; though it is sometimes blueish,
brownish, or grayish.

In all the British specimens the crystals are confusedly
grouped and small, the foreign ones being often as large as

32

the geometrical outlines. The fracture is small, rather irre-
gularly conchoidal, and has a glassy appearance. Thumer-
stone is more or less transparent, breaks easily, is rather
brittle, may be scratched with difficulty by a knife, and
melts easily without addition by the blowpipe into a lightish
green glass. Spec. Grav. 3-113 — 3*300,

by Vauquelin :

44

18

Lime

19

Oxide of Iron . . .

14

Oxide of Manganese ,

4

Loss

1

100

The crystals are found in hollows in an earthy matrix of
itself, often having a fine Asbestus covering them which
looks like Clay, but may be easily detected by being
wetted, as it is composed of extremely fine fibres. I find
also some crystallized Carbonate of Lime with the
rhombic fracture.

I am obliged to Mr. Pcnneck, Mr. Trevillian, and
Mr. Rashley, for specimens.

321

S3

TAB. CCCXXI.

CALX carbonata, var. magnesiata.
Magnesian Carbonate of Lime with Iron.

Div. 1. Crystallized.
Syn. Sidero-Calcite. Kimv. 1. 105.

This curious Mineral was long since in Mr. W. Day's col-
lection, and I have had specimens sent me by P. Rash-
leigfa, Esq. from Tincroft in the parish of St. John, Corn-
wall, as well as by another friend from that neighbourhood.
All are related to each other in the form of their crystals,
and instruct us in a series of modifications upon an acute
rhomb ; showing some very distinctly, and the manner of
accumulation necessary to form others : a very natural les-
son in Crystallography. In the upper figure are some mi-
nute perfect rhombs, resembling Haiiy's contrastante var.
of Carbonate of Lime — see the lottom left hand figure ;
while others are larger with the three faces of the primitive
remaining on the acute points or pyramids.

The middle figure shows a small truncation on the apex
of the rhomb, forming a triangular facet, which in some
Crystals is enlarged so as to cut off the obtuse lateral angles,
thus producing hexangular faces at each end. The next
magnified figure to that on the right hand shows an accu-

VOL. IV. E

34

xnulation of flat 01 plated rhombs, forming truncations upon
all the edges. The other figure shows them produced very
widely, with the sharper angles accumulating in a triangle
at both ends. This is exemplified in the lower part of
the specimen fig. 2. The Crystal in the middle geome-
trical figure is also on a large specimen that was in Mr.
W. Day's collection.

This is the Braunspath of the Germans ; but has, how-
ever, been sometimes taken for a Tin Ore in Cornwall.

Mr. W. Day observed that it did not effervesce with acids.
It is one of its characters, as a Magnesian Iron Ore, to
effervesce very slowly.

1

35

TAB. CCCXXII.

CALX carbonata, var. dodecaedra.
Dodecaedral Carbonate of Lime.

Div. 1. Crystallized.

Nature, ever instructing us with useful lessons, at first
sight often puzzles us. I had long since seen Quartzose
mixtures cast, as it were, over tabular Sulphate of Barytes,
forming a very accurate mould of them, small or large.
Such are commonly called Hacked Quartz, from the no-
tion that they resembled a substance partly chopped or
hacked with a hatchet or sharp instrument; and their for-
mation was long left unaccounted for.

It is not uncommon to find Quartz moulds, if I may so
call them, of the Cubic Fluor*, on which it often forms
coats ; and T have a very curious specimen of white semi-
opaque Quartz having formed over the Metastatic Carbonate
of Lime, from Polgooth in Cornwall, with which I was
favoured by Phil. Rashleigh, Esq.: but I had not seen Car-
bonate of Lime forming the mould of Sulphate of Barytes
till very lately. I received it from Alstone Moor in June,
1809. The specimen represented in the figure is crystallized
in the equiaxe form ; and 1 had another specimen sent at
the same time, which was cast over larger Sulphate of Ba-
rytes, crystallized in dodecaedrons with rhomboidal faces —
see tab. 128 — which is very rare: but a still rarer form is

* Sulphuxet of Iron often forms a mould from Cubic Fluor, &c
E 2

36

when truncated at the edges, as they are in the specimen
spoken of — see the right hand outline.

It is a curious lesson in the study of Chemistry to search
for the menstruum in which the Sulphate of Barytes may
he dissolved without hurting the Carbonate of Lime ; for it is
too much undercut, as the workmen would say, to deliver
the cast whole; and the facets of the Barytes are very sharp
in the mould, and indicate some rare ones that appear to
have been extremely smooth with bright and polished sur-
faces. Whether the Ochre, or other pulverulent matter
which is about the specimen, helped it to separate, I dare
not say; but I scarcely think that would have been suffi-
cient of itself.

I

II

37

TAB. CCCXXIII.

CALX carbonata.
Coralloid Limestone.

Div. 2. Imitative.

Steeple- A shton, Calne in Wiltshire, and the neighbour-
hood, afford vast quantities of Coral Rock, most of which
has the common appellation of Coral Paste. It is frequently-
semi-transparent with a waxy appearance, and the Corals
impregnated or cast in it often help the deception. In well-
chosen pieces it takes a fine polish, and often exhibits the
structure of the Corals and other things which it contains,
very beautifully, either like those found in Flint, tab. 29 1,
or some other species, of which there seems to be a great
number. The present specimens somewhat resemble, and
are even more instructive than those from St. Peter's
mountain near Maestricht, which seem to have been con-
tained in a very similar stratum. It appears that the nature
of these Coralloid Fossils has not been determined — see
Parkinson's Organic Remains, PI. xii. 1. 2. This speci-
men shows that they ought to be considered as casts with
regard to the Coral, which is evinced by the sitllce on the
case of the Mytilus, which, for the sake of distinction, I shall
call M. tunicaius. On uncovering some of these I found
specimens sufficiently perfect to develop the truth, they
having been often considered as Pholades, and lately as
Alajoriia\ but we must not allow of too much latitude for
hypothesis.

The upper corner figure is one of the cased Mytili co-
vered with remarkably formed crystals of Carbonate of

38

Lime — see the outlines near the lottom of the plate — often
having the facets, as on the outline below, mostly convex
and rounding, and sometimes bending round or enwrap-
ping the case like the left hand figure. This specimen has,
in common with others, the gramdee that betray the Bath
Limestone, tab. 8, and the partly Stalactitical Lime, as
in tab. 1, of a very white colour, and paper-like form —
see the middle figure of the second row from the bottom of
the plate — or with the fibrillce*, some tolerably distinct,
and others very minute and very beautiful ; these often re-
semble worms, and we occasionally find the remains of
true Serpulce, or a kind of worm -shell like those often
found on oysters.

The large upper figure evidently shows great variety of
casts ; the Madrepore often forms six cordate appearances
placed star- wise, with or without a column, and other
whimsical deceptive appearances. The Mytilus has its
dwelling among these, its case is variously ornamented with
them, either as stars which are the ends of the Corals, or
as strice, which are the sides of them. Within one of the
coats the hinge end of the Muscle is very distinct. The
Muscles are occasionally larger. The specimen below shows
a number of smaller ones in a smaller Coral. Both these
specimens came from Calne. The lower bottom figure was
taken out of a Steeple- Ashton turbinated Coral, the shell
having the stria? and appearanre of a fresh bivalve. The
next figure is from one taken out of the small specimen,
magnified ; and the left hand one is a cast of Carbonate of
Lime, such as is found within the shells, which determine
them to be Mytili. This is covered with an Ochre, as are
most of the specimens of Corals from Steeple-Ashton.

* These, Mr. Parkinson thinks, argue against the stellated appearances
being the remains of Coral casts; they are partly Stalactitical, produced since
the formation of the Coral, and partly the casts of minute worm-holes,

. tug iZtiafttblishUlby J.-fowrrby, Lsmsl/rn

V

39

TAB. CCCXXIV.
Chlorite Marie.

When at Sidmouth I found on the shore, nearly under the
marley rocks, a Limestone of some tons in weight, replete
with shelly remains like this specimen, which is part of
an English Boulder. This was in Mr. Day's collection,
and he used to admire it for its singularity. It is composed
of Marie and Chlorite with the Carbonate of Lime shells ;
and the chain-shot appearance of the sections of the shells
is always presented, let the stone be broken or cut on which
side it may ; which, in most other stones from Devonshire
containing shells of a similar structure, seldom happens ;
for these generally break parallel with the sides of the
shells showing their volution. The Marley Chlorite includ-
ing the shells is rather the less compact, and takes a bad
polish, as in the attempt it becomes rather browner. Upon
being fresh broken, it presents a greenish tinge, which is,
I presume, owing to the Chlorite.

41

TAB. ccexxv.

Cotham Marble.
Syn. Argillo-Calcite. Kirw.

Cotham, near Bristol, affords this remarkably figured
Marie, which, according to the Bristol Guide, you may
often imagine is a fine drawing. It is a curious formation
of Marie and Clay, chiefly stained by Iron, and perhaps
occasionally by Manganese, forming, by settling in
moisture under peculiar circumstances, the top undula-
tions, sometimes representing clouds in a sky, while the
bottom imitates earth and water as in landscapes. The
fanciful figure to themselves in this something like a boat
and men in one part, and hedge-rows in another, with trees
in full foliage. The appearance of the different parts seems
in a great measure to point out the different substances.
The whiter part is softer, and has most Lime ; the bluer or
grayer have a dilute mixture of the black Oxide of Iron ; the
browner part being still harder in consequence of the state
of the Oxide of Iron, and the quantity of Clay or Alumine ;
for it must be remembered that Clay often has much Silex
mixed with it. The deposition indicates the mass to have
been more fluid in some parts than in others ; and perhaps
some conjecture might be formed as to the trees having
distilled in drops from the upper waved surface \ but at
present we must rest with the theory, the practice of which
may lead to useful and certain truths. This substance is
found in broad slabs, and is cut transversely from the
thickness of an inch to a foot or more. It is sometimes
admired for ornamental chimney pieces, and the masons in
the neighbourhood have used a geat deal of it for such pur-
poses.

43

TAB. CCCXXVL

COBALTUM arseniatum.
Arseniate of Cobalt.

Class 3. Metals. Order 2. Oxygenized Compounds.
Gen. 7. Cobalt. Spec. 1. Arseniate.

Gen. Char. Cobalt united to Oxygen.
Spec. Char. Oxide of Cobalt united to Arsenic
Acid.

Flowers of Cobalt, commonly so called, are found at
Bruton quarry near Edinburgh, and at Alva mine in Stir-
lingshire. The beautiful soft and tufted spicules of the
upper specimen were, when fresh gathered, of a most bril-
liant satiny appearance, reflecting a fine light or dark rose
colour. The little tufts radiate from a centre nearly in a
globular form. They are extremely tender to the touch,
and lose their brilliancy in a lighter powder. Sometimes
the spicules have a flattish reflecting side or surface, and
spread in broader masses, somewhat resembling crimson
velvet or plush : they are occasionally nearly white. Tlie
middle left hand figure represents the little spicules spread-
ing in tufts. The right hand ones are of the same mag-
nified. The lower figures have the spicules somewhat la-
minated ; the left hand one being magnified. Cobalt Flowers
have lately been imported, and are very valuable. They
were first discovered in the quarries near Edinburgh by
Dr. Smith, P.L.S., when a student at Edinburgh, in 178K

45

TAB. CCCXXVIL

ARGENTUM nativum.

Crystallized Native Silver.

Class 3. Metals. Order I,

Gen. 14. Silver, Spec. I. Native.

Div. l. Crystallized.
Syn. Argent natif octaedre. Haiti/ 9 3. 385.

This specimen of Crystallized Native Silver, accompanied
by Flowers of Cobalt, was sent me from Alva mine in Stirling-
shire by my kind friend formerly mentioned in this work by
the name of G. Laing, Esq. It is a very useful specimen, as
exhibiting a very elegant arrangement of the primitive nu-
clei, if I may so call these minute octaedrons, to see which
the help of a magnifying glass is required ; and we may in-
dulge a conjecture that the Silver settled from its solvent,
whatever that was, at the time the mass was soft, which,
when hard, retained it in this state for our instruction. —
Thus we see the nuclei arranging themselves from loose or
distant order, as if preparing to form the close and com-
pact order that is sometimes seen. There being small
octaedrons placed at right angles, and then others arranging
in the intermediate spaces, is admirable. We are here in-
formed, as it were, that an accumulation of octaedrons may
be so minute as nearly to fill the interstices, seeming to

•

•

46

exclude the necessity of the tetraedrons, which, I believe,
have not been found in Silver.

Thus we have a British specimen of what is reckoned the
primitive form of Silver. The matrix of the upper specimen
is chiefly Quartzose, with some grey Silver having the Na-
tive Silver in spots or blotches, and the Cobalt in a white
and husky powder. The lower specimen consists chiefly of
Limestone, with minute crystallized Silver among the grey
Silver which is represented larger. The rose-coloured and
whiter parts are Flowers of Cobalt, or pulverulent Arseniate
of Cobalt.

47

TAB. CCCXXV1IL
Hornblend.

Syn. Common Hornblend. James. 1.357. Kirw. I.
213.

Gemeiner Hornblende. Emmerl. I. 322. 3. 267.

Hornblend is common in some of our rocks in various
amorphous forms. In this specimen, where it occurs in
its close, very compact state, it is of a greenish black co-
lour \ but as it seems to spread and become less compact, the
green hue grows more and more sensible. It is said by many
authors in this latter state to form Greenstone with Quartz
and Feldspar, or Grunstein of the Germans; but other
substances may form Greenstones : hence the necessity of
noticing it. Chlorite may be often confounded with it
when the Hornblend is divided ; but Chlorite is never so
dark, hard, or compact as Hornblend, which can with
difficulty be scraped with a knife, and composes the darker
parts in this specimen. It takes a good polish as well as
the white parts, which are hard Feldspar. The green
mixture is rather granular and softer, containing Feldspar.
This Stone has several conspicuous particles of Sulphuret
of Iron, and of Magnetic Iron. It was part of a Boulder
from a gravel-pit near York, and may be called an Horn-
blend Porphyry with Pyrites and Iron.

49

TAB. CCCXXIX.

CARBO bituminosus.
Staffordshire Coal.

In Coals we see an astonishing contrivance, not only to
preserve ancient and vast woods and forests to provide for
future contingencies, but, as it were, to the very produce
of each successive term of the former vegetable surface;
thus acres are piled upon acres and laid up in the grand
storehouse of Nature, that nothing may be lost to all -fa-
voured Mankind !

The present Coal is perhaps little else than the remains
of wood, and is comparatively but little altered in its con-
struction from situation. The more charcoal-like parts arc
rather less distinct than in the Newcastle Coal, and the
bituminous part mixed more confusedly with it, and it
upon the whole contains less foreign ingredients, as every
one may experience in the burning it. If slowly burned it
will produce ashes which exactly resemble burnt wood,
with very little chemical difference. The figure represents
the progress from the Coal at the bottom through the
cinder to the white ash. The watery parts go off in steam,
and the most volatile, the hydrogen and oleaceous parts
succeed ; then follow the more bituminous, leaving either
carbon or ash, according to the degree of heat and time of
exposure; or if burned very briskly and in a strong heat,
it might become a clinker. Thus I conceive that we have
a sort of analysis.

That Coals differ much under certain circumstances
there is little doubt ; this kind is apparently nearest re-

VOL, IV. F

50

iated to the Cannel Coal by the present analysis, only
instead of being somewhat slaty and very compact, it
has an external resemblance to Newcastle Coal, which,
however, always produces a more perfect cinder irregularly
formed, while this in the process divides into rhombic
shapes, splitting and curving into branch-like appearances
as a cinder, and becoming sometimes blunter and varie-
gated, passing totally into the shaley ash, outwardly re-
sembling wood ash, and like that very light, as it is
extremely pulverulent. I should consider this, nearly as
Mr. Mushet's Derbyshire Cannel Coal, to contain
Volatile matter . . * . . 47

Carbon 48

Ashes 4

Loss a • •••••• 1

100

Great varieties of Coal may be found in the same bed,
consequently differing in analysis, some containing Sul-
phur, more or less Earthy Matter, Iron, &c.

51

TAB. CCCXXX.

CALX Fluor, var. arenacea.
Arenaceous Filiate of Lime.

Div. 2. Imitative.
Syn. Bab. p. 24.

Fluor is not only found crystallized in company with
Quartz, Sulphate of Barytes, Galaena, &c, in aggregate
groups, but detached in very small cubic Crystals scattered
in the Lime rock — see the upper figure, where the Fluor is
seen in dark cubes scattered among brown Limestone.
Fluor is also found stratified in cubes smaller and smaller
until the eye cannot discern them, being in sand-like
grains, and finally pulverulent and undistinguishable from
their fineness, even passing dendritically among the Car-
bonate of Lime or Sulphate of Barytes. The noble-spirited
Dr. Jackson, who will always sacrifice the best of his
collection for public use, was so good as to give me a beau-
tiful large specimen of this kind with Calamine and
Galaena, the latter of which is often found in small de-
tached Crystals in the same rock with the Fluor.

The lower figure is granular and pulverulent Fluor, re-
peatedly stratified with Sulphate of Barytes, which is not
very common in an earthy form. Fluor is often of a fine
colour when the Crystals are transparent, their transpa-
rency often giving great brilliancy to their colour. The
middle specimen is a good example of a tolerably fine purple
in the granular or dusty form, which form is seldom ad-
vantageous to colour.

The specimens are chiefly from the neighbourhood of
Castleton in Derbyshire : such are indeed found in other
parts, but not frequently.

f 2

53

TAB. CCCXXXL

A R G I L L A electrica.
White Tourmaline.

This substance, which seems almost new to the whole mi-
neralogical world, not being spoken of by any author, was
sent me in 1804. It was said to be found in a mine in
St. Justs in Cornwall. I speak of it as new, being really
a white Schorl or Tourmaline ; for though Tourmaline is
said to occur of all colours included in mixtures of yellow,
red and blue, yet it is not mentioned as ever having been
found colourless or white until now ; therefore this is the
rarest known. It is transparent in the fragments, but is
so divided by cracks and flaws in general as to appear of an
opaque whiteness in parts. The form of the Crystals
agrees with that of Schorl. Their position, lying ex-
posed among Quartz Crystals, is rather new, as Tourmaline
mostly occurs imbedded in Quartz and Petuntse or Feld-
spar.

The late Hon. Charles Greville, who is much to be la-
mented from a loss I particularly sustain in the intimate
recourse he allowed me to his specimens, pointed out the
idea of my specimen being a white Schorl at the time I
first showed it to him; even that recollection adds value to
the specimen by putting me in mind of a valuable friend,
I never could procure a second specimen, or he would have
possessed it. I do not know that he ever procured any. I
believe Mr. Herbert, who kindly presented me with this,
has one also.

Among the small Crystals on this specimen is one that
most happily shows the primitive on its end almost de-

54

tached, as if it were done on purpose, nearly as figured in
the outline, which gives it the appearance of lying fitted
on the column; indeed the two acute ends are partly trun-
cated by the narrower faces of the octagonal column.

The right hand outline shows the faces of the pyramid
and column, which are very distinct.

The left hand figure represents the modifications of
some of the other small Crystals, with three oblique faces
not before observed by any author, — the thin outline and
shining part shows one of them : it was done thus, in order
that it might be known most distinctly.

1

55

TAB. CCCXXXII.
Granite. '

Class 2. Earths. Order 2. Aggregate.
Gen. Petuntse. Spec. Granite.

Syn. Roche Feldspathique. Hauy^ 4. 430.

This Granite is considered as of the primitive formation ; ic
was once brought from Siberia as a great rarity, and cut for
seals, &cc, at a handsome price, though not perhaps ex-
travagant, being brought so far : it however happens in this
instance, as in many others, that where curious minerals
are sought for abroad, the same are to be found at home.

Monymusk in Scotland affords many beautiful varieties.
One of the characters of Primitive Granites is the crystal-
lization of its component substances; the two of which
this is composed are, as it were, coeval in the act of crystal-
lizing, and each in part prevented the other, which gives it
the particular appearance in these varieties, said to re-
semble the letters of the Greek alphabet, though to me
they rather represent in form the Hebrew characters : — they
have, however, been termed Graphite and Siberian Greek
Stones most commonly.

The crystals of the Ouartz occasionally terminate in such
a manner as to show their facets, and they often present
themselves remarkably flat, with a perfectly concordant
structure, and even new facets : — -thus the shaded face in the
upper left hand outline is at present new to this substance,
more particularly as being placed on the middle of one of

56

the pyramidal faces : — there is some indication of it in
some of the Crystals of tab. 319.

The position and angles of these Crystals caught in the
fracture of the Petuntse give the curious appearance. The
Petuntse has rather an amorphous appearance in general,
but is all crystallized; and when the large primitive sides
are reflected to the eye, they show its beautiful and pe uhar
lustre. It sometimes shows the terminations. The Quartz
varies in colour from transparent to gray brown and nearly
black — the Feldspar, from white to reddish and brown.
Mica is found in moderate-sized specimens. Two of the in-
gredients would constitute it a Granitel; three, a Granitine
of Kirwan: but these distinctions are not really of conse-
quence ; and I am afraid the term Sienite is not much
better, unless perhaps as an original term used by Pliny.
It is understood chiefly to consist of Feldspar inclining to
red, and Hornblende, and sometimes are added Quartz and
Mica, as 1 and others have it from Egypt ; myself by fa-
four of Mr. W. Morel, being detached from one of the
pillars at the entrance of the temple of I sis in the ancient
Canopus near the fort of Aboukir. Its structure is that of
Granite with the addition of Hornblende in a small propor-
tion.

UQty /iu/)ffM b/J Jcr J formerly JL'iidlon.

57

TAB. CCCXXXIII.

Sienite.

Class 2. Earths. Order 2. Aggregate.

Gen, Petuntse. Spec, Sienite.

This, although very different in appearance from what is
to be expected in Sienite, agrees as to the ingredients,
especially as being composed chiefly of Feldspar and Horn-
blende ; the latter being more or less in partly formed black
Crystals. The Feldspar is grey with a blue iridescence,
which is better conceived than figured. The iridescent
faces of the Red Feldspar sometimes possess this lustre
most beautifully, and I have specimens which I picked up
in the road in my neighbourhood, which I suppose to be
more rare than the present, which I purchased at the late
museum at Yarmouth, as brought from near Aberdeen in
Scotland. This is, according to some, a Porphyritic Gra-
nite; the Feldspar being relieved by the dark ground gives
it a porphyritic appearance.

This is sometimes called Scotch Labradore Stone, on
account of the iridescence, which is of the same nature in
the grey Feldspar of Labradore, though they are much
more brilliant and varied in their colours.

3M.

59

TAB. CCCXXXIV.
Schiller Stone.

Syn. Schiller Spath. Emmerl 3. 340.

Spath chatoyant des Allemands. Haiiy, 4. 395.
Schiller Stone. Jameson, 1. 428.

Already mentioned at tab. 221. This substance is not
much known, and although tolerably easily detected when
in Serpentine, is not otherwise much unlike some sorts of
Hornblende; it is, however, much softer, and is rather easily
scratched with a knife, giving a white streak somewhat
metallic in lustre, and having a plated appearance. In
the British specimens, either from Cornwall or Scotland,
the plated structure is more or less readily seen in numerous
brilliant specks, from the tenth of an inch to upwards of
half an inch in size : the larger plates have frequently a
broken or ragged appearance, with holes in them penetrated
by the duller Serpentine, or its flat surface forming round
about the rugged earth, which often accompanies the dark
brick-coloured Serpentine.

The plates seem very thin, and accumulated upon each
other ; and this is partly seen in some rhombic sides, re-
sembling some slaty structures : on the other sides it is
not at all discernible. The substance on the whole is of a
dull blueish green, or middle greenish grey — see my Elu-
cidation of Colours, tab. 5 and 6, No. 47*. The plated

* It is usually called Olive green ; but olives differ very much. I feel con-
fident that a table for colours and reference will be most exact.

60

faces reflect yellowish and reddish illinitions, probably from
the position and colour of the matrix. Its peculiar glance
is pretty well represented when we see the whitish shining
appearance of the print. The substance itself is chiefly
recognizable by this glare. On Charcoal with a blowpipe
it melts into a black enamel, difficultly when compact, but
more easily when in a looser and rather decomposed state,
when it is generally of a reddish hue. It has often been taken
for Hornblende : it looks very like some Feldspar in its
peculiar lustre; and I have seen Carbonate of Lime some-
what resembling it, in the coarser crystallized masses of
rocks.

Mr. Hatchett is said to have first observed it in the Ser-
pentine of Cornwall ; and I have received specimens from
my kind friend Philip Rashleigh, Esq. ; and this month I
received a specimen gathered by Mr. Jackson in Montrose,
Scotland,

61

TAB. CCCXXXV.
The Alluvial Depositions forming Soils.

Class 2. Earths. Order 3. Mixed.

The surface of the Earthy alluvial or vegetating Debris, so
admirably contrived by the laws of Nature for our agricul-
tural use, have scarcely been attended to by Mineralogists,
and in general make so small a part in their works, that they
would seem to be of little consequence ; and the import-
ance of a more accurate knowledge, and the very use of
them in vegetation, has even been superseded by many chi-
merical ideas. Nature kindly allows, and even invites us,
to show industry and sagacity in many instances, but we
must be heedful not to mistake her contrivances.

The top figure is a representation of a very fissile rock of a
nature scarcely noticed : it is a variety of clayey Shale, con-
taining a small portion of Iron and Bitumen : it crackles in
the fire, and when red-hot produces a little flame. The
outside passes in colour from blackish to a lightish rusty
brown ; it splits and falls to pieces in the weather, forming
at its foot a soil very different from the original appearance
of the rock— see the representations under it. I had it from
Bakewell in Derbyshire, where it is considered as excellent
for Firs, Elms, and Fruit Trees. The Bakewell Rotten
Stone, tab. 240, is a curiosity in its agricultural character;
it is well known to produce white Clover spontaneously
the second year after its being formed into meadow. Oaks
do not thrive in it : it is a good manure for gravelly soils.

The right hand lower figure represents a part of a red
rock from Beaumares in North Wales. It has very much
the appearance of a baked tile. The fresh soil formed from
this is reckoned very fertile : it forms crumbling lumps —
see the left hand figure — chiefly composed of Silex, Clay,
and Oxide of Iron.

62

TAB. CCCXXXVL
Moulds.

The genius of our country, often so happily exerted in
agricultural pursuits, has yet much to do in regard to one
of the first sources of vegetation; I mean the Mineral
Kingdom or Department, which assists vegetation, the link
of life, and support of the Animal Kingdom. The example
of old ground not requiring manuring is not common.
I am glad here to show one in the upper figure, which re-
presents Mould from Wilson field near High Wycomb,
Bucks, which produces regularly fine crops of wheat with-
out manure, and had so done for eighteen years in June
1801, when Mr. Allen gave me the specimen. It may be
remarked, that among some hundred kinds which I have
examined > I have not seen one exactly resembling it, and
therefore I presume to hope that external characters may
be of more importance in this subject than has hitherto
been suspected. It is evidently mixed with Chalk in little
pieces. The Silex seems to be in very small grains held
together by common Clay and vegetable Mould.

The right hand figures are from Orcheston St. Mary, about
two miles from Salisbury, famous for producing extraor-
dinary crops of Long grass. Excluding the small bed of
loose pebbles, which is a common washed gravel found
beneath, I have figured the Mould as it is immediately
connected with the roots of the plants, an inch or two in
depth. It seems to be fine sand, held together by Clay
mixed with fine dirty Chalk and vegetable remains, some
parts full of roots, ana 1 others more detached and easily
separated. Its situation allows of much water occasionally,

63

which of course fertilizes it ; but it has still a different ap-
pearance from any other Earth I have met with. The de-
tached pieces adhere rather strongly, and are rather hard
to break ; a character which I have known brick-makers to
call water-bound. I believe it to be a vegeto-carbonaceous
binding, if I may term it so.

The next left hand figure is a soil from Shrewsbury with
which I was favoured by Colonel Green. Its peculiar ap-
pearance caused it to be noticed. It is a very fine, but
looser Earth than cither of the former; perhaps has less
common Clay, and it appears to show more Chalk with
Siliceous pebbles; and it connects its particles so as to
leave hollow interstices, although often in largish frag-
ments. It produces good wheat, barley, &c. Tfie lower
right hand figure is of a fine Earth for Oaks from Lord Fitz-
william's fine Oak-park about nine miles from Sheffield,
Yorkshire. It is a light ochraceous Loam, chiefly Clay
and fine Sand coloured by a lightish Oxide of Iron with
some vegetable Earth. It is remarkable for an astringent
bitter taste, resembling Bark. The largest Oaks in Great
Britain are found in this park. The left hand lower
figure represents a Mould brought from near Bridgenorth
in Shropshire by my friend Mr. Charles Stokes. It is re-
puted as very fertile for Barley and Wheat, and for retain-
ing moisture when most of the neighbouring lands are dry
and sterile. There is a remarkable gravel terrace near it.
The red appearance with a peculiar softness in the aspect
makes it noticeable. It is mostly Sand mixed with Clay
and Red Oxide of Iron, and does not seem to have much
Lime or Vegetable Matter among it.

The analyses of Vegetable Earths, &c, are well treated
of in many books, particularly Kirwan's Essay on Ma-
nures, and II. Davy, Esq., for the Board of Agriculture.
It is, however, desirable to gain as much knowledge as
sre can of a soil by figures and practice also ; otherwise we

64

cannot compare one soil with another, or the part of a
soil analysed with the land from which it is taken.

Lapidaries guess pretty well of hard Stones by sight with
practice, so should those concerned in agriculture. Indeed
it would be very convenient if we could compare a written
analysis, for instance, soil taken from Sheffield Place,
remarkable for producing flourishing Oaks, analysed by
Davy, and found to consist of

. 54

Alumine . . ,

. 28

Carbonate of Lime

3

Oxide of Iron . .

5

Decomposing matter

4

Loss .

3

100

and the Oak soil figured from Yorkshire : we might con-
ceive the five parts of Oxide of Iron to give the colour;
the Silex grittiness ; the Clay unctuosity ; the Lime taking
a part from its unctuosity as well as the Sand ; the Vegetable
a soft matter distinguished from both by a rotten and car-
bonaceous appearance. According to experience, his Oak
land would to me differ in being a little lighter-coloured,
having a little more chalky whiteness, or having a little
more Lime than ours contains, and perhaps being of a
finer grain. This may be learned best by experience \ ana-
lysis may prove it.

65

TAB, CCCXXXVIL

STANNUM oxygenizatum.
Oxide of Tin (in veins in Schist or Killas).

Class 3. Metals. Order 1.

Gen. 5. Tin. Spec. 1. Oxide.

Div. 3. Amorphous,

Syn. Tin veins in the Killas, or argillaceous Schist.
Kinv. 1. 237.

It is very instructive to see the form of the Tin veins and.
their direction with regard to the formation of the Schist
or Slate, they being either straight, or curved in a remark-
able manner, and usually crossing the laminae of the Slate,
The upper specimen came from St. Agnes in Cornwall,
and consists of the coarser Killas*: the oblique position of
the veins in the larger specimen shows it to be from a
lower part of the primitive Slate formation than the under
figure, in which they are finer and more parallel, being of
a rather later formation.

* Killas is the Cornish term for the primitive Sohist in which Tin is found.

VOL, IV.

66

TAB. cccxxxvm.

The upper figure came probably out of a large vein of
Tin, and is what the Cornish miners call Shoad Tin. It
occurs in the neighbourhood of the primitive formatioa
among alluvial deposits from it. It is much the same as
that in the veins, composed of more or less confused
masses of Crystals. These, and even the perfect Crystals,
are often found worn into pebbles in the streams, and are
termed Stream Tin, resembling common Flint Pebbles,
or Gravel Stones. They are of different colours, as here
figured, and may best be known in the first instance by
their superior and extraordinary weight in the hand. They
are also called Grain Tin when in grains or very small
portions.

The streams are often conducted with much attentioa
over chasms and small valleys to the lower grounds, where
means are contrived, by washing, to collect large quan-
tities, separate from the mud and other matters, and equal
to that obtained by mining. There is moreover less trouble
in the separating and breaking for smelting.

67

TAB. CCCXXX1X.

STANNUM sulphureum.

Sulphur et of Tin.

Class 3. Metals. Order I.

Gen. 5. Tin. Spec. 2. Sulphuret.

Div. 1. Amorphous.

Syn. Tin Pyrites. Kirw. 2. 200.

Sulphuret of Tin. Babington^ Cat. 214.
Zinnkiess. EmmerL 2. 418.
Etain sulphure. Haiiy, 4. 1 54.

This was, and still is, a rare substance, and is only yet
known as found in Cornwall ; first at St. Agnes in the time
of the celebrated Klaproth, in a vein about sixty feet below
the surface, and nine feet wide ; and since somt has been
found at Huel Scoria.

The upper specimen was brought from the former place,
and, according to Klaproth, was found in what is called
Growan by the Cornish miners, which is decomposed Feld-
spar of the Granite rocks: — see lab. 224. Rasp, whore-
sided in Cornwall at the time, gave it, because it contained
much Copper, the name of Bell Metal Ore. To Bell Metal
it bears some resemblance, and is brittle like that. In so
large a vein it must be supposed to vary a little, being
occasionally grayer or yellower, with more or less Copper:
Klaproth observes that Rasp's name would be more just if
there were a larger proportion of Copper to the Tin. The

o 2

68

varieties of course admit of some allowance, and each may
be right; but their specimens probably differed.

The lower figure is of a regular texture and smaller grain ;
it came from Huel Scoria, by favour of my kind friend
Mr. R. Phillips. There is among it something like Mis-
pickel, or Arsenical Iron, of a grayish white colour : — see
Descr. tab. 150. It has a bloom and dark tarnish on the
outside. I was lately favoured with a specimen by my
kind friend the Rev. W. Gregor, from Huel Rock in
St. Agnes's parish, which is a mixed specimen, including
Sulphuret of Copper and Iron. It had some indications of
the Growan matrix about it.

Klaproth's analysis seems perfectly to agree with this

substance, as under:

Tin 34

Copper 36

Sulphur 25

Iron 3

Earth 2

100

It is arranged by most authors as Sulphuret of Tin, al-
though this analysis gives more Copper than Tin ; but the
Copper is generally thought to be merely mixed with the
Sulphuret of Tin : indeed its granular texture prevents a
complete separation from the Copper Pyrites that accom-
panies it.

69

TAB. CCCXL.

COBALTUM oxygenatum.
Oxide of Cobalt.

Class 3. Metals.
Gen. 7. Cobalt.

Order 1.
Spec. 1. Oxide.

Div. I. Amorphous.

Syn. Black Cobalt Ore. Kirw. 2. 275.
Native Oxide of Cobalt. Bab. 232.
Schwarzer-erdkobolt. EmmerL 2. 498.
Cobalt oxyde noir. Haiiy, 4. 214.

On the estate of Sir John Thomas Stanley, Bart., at AI-
derney Edge in Cheshire, was found this variety and mix-
ture of Cobalt, The substance being now so very scarce
and valuable, the knowledge of this variety is of the more
consequence, as it may lead to the finding this Mineral on
some unexpected occasions. The bloom of Cobalt having
the crimson cast, is apt to betray it, and I hope, for the
owner's sake, this may become more profitable than hitherto,
and lead to the acquisition of the more perfect substance.
This is so mixed with Sand, Oxide of Copper, Manganese,
&c, that it is of but little value as an Ore of Cobalt.

i

71

TAB. CCCXLI.

PLU M B U M sulphatuni.
Sulphate of Lead.

Div. 1. Crystallized.

These peculiar green Lead Ores have created some con-
fusion among Mineralogists, from their having been con-
sidered by several as Molybdates of Lead*, which, I be-
lieve, we have not yet found in this country. I was fa-
voured with the present specimen from Wanlock-hcad by
G. Laing, Esq., who has so often kindly given me occasion
to mention him in the course of this work.

The Crystal is a long rectangular prism placed upon one
of its sides. Two of its faces, the upper and lower, are
primitives ; the larger two terminal faces are also primitives,
being the sides of a rhomboidal prism ; the middle of the
three smaller faces is on the acute solid angle, the other
two are on the succeeding, or the thus newly made solid
angles. We find this to be the same primitive as tab. 153,
which upon further examination proves to be also a Sulphate.
Its insolubility in hot Nitric Acid diluted, confirms its
being a Sulphate, besides other trials, by some of which
we are led to suspect a small portion of Muriatic Acid ; but
we had too small a morsel to try it perfectly f.

The green hue of the present specimen may depend upon
Oxide of Iron, or some foreign ingredient.

* Found in Carinthia.

f It would be very desirable that Mr. Gregor, Dr. Wollaston, or some such
person, in whom we may place confidence, would examine these substances.

73

TAB. CCCXLIL

PLUMBU M carbonatum.
Carbonate of Lead.

Div. 1. Crystallized 5 in hexaedral lamince.

Carbonate of Lead of this form and colour has for
many years been considered as a Molybdate. Its readily
effervescing in dilute Nitric Acid will, however, betray it.
The modifications of the present specimen are remarkably
striking, and are evidently to be traced from, or to, the
plated forms of tabs. 89, 90, and 91. The Crystals have a
light glare, and somewhat pearly lustre, and are in colour
from nearly white to greenish yellow j scattered in irregular
fissile hexangular plates, or more compact : — see the middle
figure, which contains plates nearly like the lower left hand
outline, or piled up as that on the right hand.

These specimens are very rare, and occur only now and
then in the Wanlock-head mines near Glasgow. I have
one from Mr. Day's collection, some years old ; and some
by means of other friends. I do not know that they are
found elsewhere, or arc at all described as green, or ap-
proaching thereto. They are said to be snow-white, grayish
and yellowish-white, cream-yellow, and clove-brown.

WM

I

75

TAB. CCCXLIII.

• VISMUTUM nativum,
Native Bismuth.

Class 3. Metals. Order 1.

Gen. 13. Bismuth. Spec. 1. Native.

Dii>. 1. Crystallized.

Syn. Vismuthum nativum. Waller, 2. 205.
Gediegen wismuth. EmmerL 2. 434.
Native Bismuth. Kirw. 2. 264.
Bismuth natif. Haiiy, 4. 184.
Vismutum. Linn. ed. 13. p. 128.

This is a rare substance as British. It came from Corn-
wall, and was among the specimens T had the good fortune
to procure of the late truly ingenious Mr. Day. It appears
in the centre of Amorphous Brown Quarts. It has some
admixture of gray or dark Sulphuret and other substances,'
perhaps Cobalt, with Oxide of Iron, &c. At Johann-
Georgenstadt and Sneeburg in Germany, it is sometimes
found crystallized in four-sided tables, in somewhat cu-
bical or truncated tetraedrons. Its primitive form is an
octaedron. The colour of the present varies from whitish
to tarnished yellow, reddish or purple ; metallic fracture
more or less perfectly foliated, folia parallel to the planes
of a regular octaedron. The peculiarly beautiful crystal-
lization of this substance obtained by melting it in a proper
degree of heat, and then suffering it to cool, attracts at*

76

tention : — see the lower figure. The square or right-angled
volute might afford an excellent natural lesson or model for
a square column, pilaster, or frieze, in the hands of a
good architect. I conceive the original and best forms of
the ancients were derived more from natural subjects than
is generally thought.

77

TAB. CCCXLIV.
VISMUTUM carbonatum.

Class 3. Metals. Order 2. Oxygenized compounds.
Gen. 13. Bismuth. Spec. I. Carbonate.

Div. 1. Amorphous.

This common earthy-looking substance, being chiefly
Carbonate of Bismuth, with a little Oxide of Iron, and a
very little stony substance, came to me by favour of the
Rev. W. Gregor, from St. Agnes, Cornwall. That gentle-
man, often usefully employed for his amusement in ana-
lysing minerals, is an honour to his country. We think
it of much consequence to figure such a substance as the
present; for, by remembering the figure or the substance,
we shall not too hastily pass over things which at first have
common appearances ; but examine them with attention,
which will habituate the judgement to the easy discrimina-
tion of obscure characters, and teach us to suspect what is
not quite usual, and therefore to examine it, if necessary,
by means of chemical agents.

Nature, in this mineral, seems to point out something
of the soapy appearance of Steatite: — see tab. 222 ; but
it is more earthy, or rather harsher to the touch, though
the Oxide of Iron in some parts disguises it. The
weight in the hand seems greater than that of Steatite. As
Oxide of Bismuth has been found a most beautiful and
pleasant pigment for high-finishing water- coloured draw-
ings, and as the present specimen does not apparently
change colour, as that does, on exposure to light, I was

is

led to think it might afford a lasting pigment, and instead
of spoiling many a highly finished drawing, and operating
to disgrace the artist, Bismuth might be brought to re-
cover its own fame in the form of a Carbonate, and be a
lasting memorial of the spirit of the artist's touch ; but
upon trial I have not found the artificial Carbonate a*
all equal in lu6tre to the Oxide.

SI

TAB. CCCXLV.

CALX carbonata ; van fibrosa.
Fibrous Carbonate of Lime.

Div. 2 Imitative.

This substance has been long known ; but, I believe, ha*
not been noticed in any publication, if we except Dr. KidcTs
Outlines of Mineralogy. I have a piece in my possession
which is reported to have belonged to Da Costa, who was
said to be at a loss what to call it. I have also received it
from different friends at various periods; which shows it to
be sufficiently remarkable to attract notice, and that it
would appear a desideratum if passed over in this Work.
It was probably first noticed at Bath, or in the quarries in
that neighbourhood ; but is also found in most Limestone
quarries, varying much, accordingly as the stratum in which
it is found is more or less compact. I gathered the upper
specimen at Shotover Hill, where it is not uncommon £
but these were rather remarkable, as the fibres were mostly
so very loose as to resemble in texture some rotten wood,
which has lost the transverse fibres, and become petrified.
It separates into extremely fine filaments, which, after se-
parating, break so nearly, if not quite, transversely, as not
to show in the least the rhomboidal fracture (a character
peculiar to it and the Satin Spar). The middle figure shows
the varieties of its colour, from nearly white to the
usual brown \ and wa3 sent from near Bath. The
lower figure is taken from a specimen found at Mit-
ford, with which I was favoured by Thomas Meade, Esq. 1 *

* I beg to correct a mistake in this gentleman's name ; — it should alwayi
be read as above, not Charles, and should have the terminal c,
TOL. ir. H

82

Tt is remarkable for the bending of its filaments, and nob-
less so for the holes apparently formed by the Mytilus tu-
nicatuSy (which I find abounds in variety of petrified Corals,
&c, found between Oxford and Bristol, — see tab. 323.)
There are also cases of Serpulce about it. This proves that
the structure of the substance preceded that of the Mytilus,
and that it may have been coeval with the Corals, or even
of earlier formation. It is sometimes dull and opaque,
sometimes almost transparent, and nearly as shining as-
Satin Spar*.

* I must here remind my readers, that the habitat I have given for Satin-
Spar, tab. 5, 11, is correct; for some other authors have, by mistake, and
by copying from each other, named Derbyshire for its habitat, and this
seems to have originated with Jameson, who probably purchased some speci-
mens there, and where, not long since, has been found striated Gypsum or
Sulphate of Lime, so compact as much to resemble the Satin-Spar, and like
it has been cut for ear-rings, necklaces, &c. The former may be readily di-
stinguished from the latter by being easily scratched by the finger-nail,

63

TAB. CCCXLVL

CALX carbonata.
Incrusting Carbonate of Lime. Osteocolla.

Div. 2. Imitatire.
Syn. Osteocolla. Enc. Brit.

Chaux carbonatee incrustante. Haiiy^ 2. 172.

Osteocolla being mentioned in most modern books, it
may naturally be inquired for in mine : and as I should hope
not to be wanting where there may be information given, I
herewith exhibit a figure of this substance, which is more
than ordinarily instructive, although only a variety of Sta-
lagmite. The present specimen was found near Shotover
Hill, and shows the curious mode of its accumulation,
especially as the substance of the branches is yet distinct.
It is called Osteocolla from being supposed to have a power
of uniting broken bones. It may vary with the nature of
the current that deposits it. This specimen has a peculiarly
soft and chalky, somewhat woolly, appearance. It is
nearly of the same nature as the deposit in a tea-kettle;
but that is harder, and may give an idea that it depended
on the water being heated. We find these depositions to
be generally about this hardness, or perhaps a little harder
and rather more compact. Westminster Bridge has a settling
of the Lime from the water on some parts of its sides of
a curious undulating figure ; and moss with many other
subjects, such as birds-nests with the eggs, are covered in a
similar manner at Matlock and Knaresborough, first settling

H 2

84

on the outside, and then accumulating as the substance
sometimes rots. This is especially the case in Moss, when
it seems to have taken the entire figure of it. I add a spe-
cimen of the Moss \ but there are many varieties, some
even showing the species by the cast over it. Sometime3
the splashing of the water falling from a height heaps the
small grains on each other, and forms natural grottos. The
specimen ji-gured leloiv, having been deposited in the place
of a nut kernel, is truly beautiful. I was favoured with it
from Knaresborough by the Rev. W. Danby, accompanied
by reflections upon it, such as the contrivances of Nature
generally excite in a truly enlightened mind. Lady Wilson
has lately brought me some granula of Carbonate of Lime
deposited in water used at Charlton House, which are very
small, resembling common sand, and which help to show
that Ketton Stone is merely a deposition of the same kind.
Is it the disturbing of the water, or any particular motion,
that might cause the Lime to form granules ? We have
great variety from this to the Botryoidal stones found in
Rutlandshire of a large size : — see tab. 284.

1

85

TAB. CCCXLVII.

CALX carbonata.
Calcareous Schist,

Div. 3. Amorphous.

The term Slate Is applied to very different Stones ; but it
is more generally understood a3 belonging to the blue or
gray Slate, commonly so called when it is even a term for
colour, as Slate-colour; but this term does not lead to
accuracy, as Slate is found to vary in this respect. Colour
formerly helped to distinguish the species for common use;
but now many varieties, both in colour and texture, are
used ! While Slates are common in some counties, in
others the people are strangers to them ; and luckily find
Limestone so fissile as to serve for roofing their houses j
and this, being schistose or slaty, has obtained the appella*
tion of Slate.

The lower Jig ure came from Stonesfield, Oxfordshire,
and has often in its fissile divisions shells, sharks' teeth,
and other things of this nature. These Stones often have
fishes' teeth in them, perhaps most remarkable at Verona
in Italy. When Stones for building are chosen from these
quarries, it becomes necessary to place them nearly as they
were in their native places, else by exposure they split per-
pendicularly, and fall from their places in flakes; which
may occasionally be seen in Limestone buildings.

The small upper specimen was found about 2 or 3 feet
from the surface in Sussex, and furnishes strong argument
for its very recent formation. Little petrified shells, re-

86

sembling the minute stagnant pool muscle or bivalve, if
not one of the same species as now exists, cover it in every
division very abundantly; and like other fissile Stones, the
bivalves show the convex on one side and the concave on
the other. I am obliged to my friends Messrs Borrer and
Weeks for the specimens in my cabinet. The next specimen
is from Stonesfield, a quarry famous for a great variety of
animal exuviae, especially of the genus Cornu ammonif.
This has an alligator's tooth finely preserved. If we may
be allowed to judge from the teeth, there have been many
species of alligators enveloped in the catastrophe that made
such wonderful havock. The other two pieces, the upper
of which is without any appearance of petrifaction, are a
sort which is often divided by very silvery-looking Mica
covering the fissile surfaces, and mostly accompanying the
more sandy sort : — we find by Lady Wilson that it ap-
proaches even to a Jasper. The lower specimen has casts
of different bivalves, and has a hole in the top, which shows
in a small degree the manner of manufacturing them for
Slates. Several of the above specimens contain a consi-
derable portion of Sand. All Limestone quarries have a
more fissile Stone near the top : those of Portland, Purbeck,
and Bath are generally shelly, and sometimes merely a
congeries of compressed shells almost as thin as paper.

1

pa

87

TAB. CCCXLVIII.

S I L E X talcum.

Massive Talc, Potstone, or Lapis-ollaris.

Diu. 1. Crystallized.

Syn. Potstone. Kirtv. 1. 155.

Lapis-ollaris. Waller. Bab. Miri. 39.
Talc ollaire. Haiiy, 3. 257.
Topfstein. Emmerl. 3. 282.

Although this is not a rare substance in countries where
Serpentine Rocks occur, it is nevertheless often too un-
equal in its nature to answer the purpose of turning into
pots. In Scotland it is abundant ; and the Duke of Argyle's
house at Inverary is said to be built of it; yet it is but little
known. I have seen sets of tea equipage, and I have a
tankard made of il from abroad ; and in Saxony it seems that
hundreds of people are employed in manufacturing it. The
usual kind abounds with Talc, and is of an even and close
texture ; but that which is used varies much, and more or
less approaches Talcose Schist and Serpentine. Some of
the cups which I have from Italy seem to be a Talcose
Schist, with Garnets of such an equal state of hardness,
that the whole turned equally well.

The upper figure is a representation of a specimen from
Ereadalbane of the common texture; but the fibres are
rather more than usually varied in their direction, so as to
make it nearly free to cut or turn to any form.

The lower figure is a more Schistose variety, from the

88

same place, commonly called Schistose Potstone. The
different kind of Potstones vary much in colour.

I have figured this substance rather as a mineral than as
a specimen of such as is turned in the lathe, although it
would answer the purpose pretty well in a certain pro-
portion. Its stellated formation is rather rare ; I have not,
however, represented that variety : but, from what has been
said, it may be readily understood that there may be nu-
merous varieties ; and those of the most equal texture
throughout are to be preferred. They are generally some-
what porous, and sometimes do not hold water better than
the vases, &c, made in Derbyshire and ether Fluor countries.

The inhabitants of New Caledonia occasionally use a
sort of Potstone Steatite to assist them in the place of food
when it is scarce.

I wonder that there are no such Potstone manufactories
in Great Britain as those in Saxony; for I think there is
but little doubt of procuring the Stone as likely to answer
this purpose as the foreign sort. Perhaps, however, there
would not be a sale for them.

mm

89

TAB. CCCXLIX.

ZINCUM sulphatum.
Sulphate of Zinc.

Class 3. Metals,
Gen, 4. Zinc.

Order 2. Oxygenized Compounds.
Spec, 2. Sulphate.

Div, I, Crystallized.

Spec. Char. Oxide of Zinc combined with Sul-
phuric Acid.
Syn. Vitriol of Zinc. Kinv. 2. 23.
Zinc sulphate. Haiiy, 4. 180,

Sulphate of Zinc is found at Holywell in Flintshire ;
and the specimens which I have were brought from thence.
It is formed on a red earthy Oxide of Iron, and is chiefly
distinguished from the Sulphate of Iron, or Copper, by its
whiteness, being commonly called White Vitriol and even
White Copperas. I have not seen it crystallized in its native
state. It is slightly laminous in its fracture, and is formed
rather irregularly in holes or foramina. It is soluble in
twice its weight of cold water, and has a strong styptic
taste. When pure it consists of

Oxide of Zinc . . . 40*

Water . . . .
Sulphuric Acid .

39'5

20-5

100-0

I;

1

91

TAB. CCCL.

FERRUM sulphatum.
Sulphate of Iron.

Div. 2. Imitative.

The upper specimen is a remarkably fine Stalactite from
Cornwall, and has been in my possession many years
without having apparently undergone any alteration, which
is seldom the case. I have shown specimens in Plates 23
and 28 which have a very different appearance. It is
commonly called Green Martial Vitriol, is usually soluble
in twice its weight of cold water, and less than its weight
of boilincr water. It is said to have a double refracting?
power in proper and transparent Crystals. It is used for
making ink with oak-galls, and gives it a peculiar astrin-
gent taste. It produces black with any vegetable, and is
a styptic. The specimen figured above has some signs of
the primitive rhomboidal angles about it.

The lower figure is taken from a North Wales specimen :
it is more apt to decompose, and shows the changes it un-
dergoes under these circumstances, as it becomes yellow or
brown, sometimes crumbling into a Sulphur yellow. The
primitive Crystal is somewhat apparent about this specimen;
but the lowest figure is most perfect in that respect; such is
sometimes found in Cornwall and Derbyshire. Di. Kidd
mentions finding it in the Shale that overhangs Odin mine
at Castleton in the latter county. Sulphate of Iron is often
of a fair green colour, (see Elucidation of Colours) lighter
or darker, by which it is known from Zinc, which is nearly

white, unless coloured a little with Iron or Copper. Sul-
phate of Copper is always much bluer, and approaches the
Sulphate of Iron, if adulterated by Iron, which often hap-
pens. Spec. Grav. of Sulphate of Iron 1-83.
Analysis according to Kirwan :

Oxide of Iron
Water

Sulphuric Acid

46
26

28

100

1

93

TAB. CCCLI.

CUPRUM sulphatuni.

Sulphate of Copper, or Blue Vitriol.

Class 3. Metals. Order 2. Oxygenized Compounds.

Gen. 12. Oxide of Copper. Spec. 3. Sulphate.

Div. 1. Crystallized.

Spec. Char. Oxide of Copper combined with Sul-
phuric Acid.
Syn. Vitriol of Copper. Kirw. 2. 22.
Cuivre sulphate. Haiiy, 3. 580.

According to my specimens, which I have had many
years, this is found in those rocks which are usual in North
Wales, in which Cubic Pyrites so much abound, and is
occasionally adulterated by the Iron. Tt is most pure when
nearly deep blue with a greenish cast ; but is sometimes
lighter coloured, as figured. It is less soluble than Sul-
phate of Iron, requiring four times its weight of cold water,
and twice its weight of boiling water for solution ; it is also
styptic to the taste* It may be artificially procured of a
vivid and rich blue] but always having a greenish cast.

The upper figure gives the most usual appearance of it
upon the rock. The specimen figured below was, when
first gathered, of the beautiful blue cast of the fresh
broken inner part; probably some Oxide of Iron is the
cause of the outward change of colour, which, however,
doest not penetrate far into it. The best Crystals are formed

94

artificially. The primitive form is a parallellopiped with
oblique angles: — see the bottom outline. Spec. Grav. 2* 19*
Analysis by Mr. Kirwan :

Oxide of Copper ... 40

Sulphuric Acid .... 31

Water 29 s

100

Although water is necessary to this substance, as well as
to the Sulphates of Iron and Zinc, and might be considered
in sufficient proportion to make them aqueous species ; yet
we rather think the specific appellation best given from the
Sulphuric Acid, as most essential to their nature.

95

TAB. CCCL1L

S T A N N U M oxygenizatum.
Hcematitic Oxide of Tin. Wood Tin.

Class 3. Metals. Order I. Homogeneous.

Gen. 5. Tin. Spec. I. Oxide.

Div. 2. Imitative.

Syn. Fibrous Tin Stone, Wood Tin Ore. Kirw. 2.
198.

Etain oxyde concretionne. Haiiy 9 4. 147.

The peculiar haematitic structure of this Ore of Tin, or
rather the radiated structure that often attends the Haematite
or Iron Ores, having a woody appearance, has given rise to
the name, which serves very well upon the whole, although
we do not think it very apt, considering its hardness and
specific gravity. In its usual state it may most readily be
distinguished from Iron hy merely weighing it in the hand.

Tlie upper specimen is magnificent as to size, being very
rarely found half so large. It was lent me for this public
use by Edward Hawkins, Esq., who possesses a fine assort-
ment, and is inferior only to one in the Greville collection.

The right hand lower specimens are of the most usual size;
the left hand one shows the concentrating radii- with the
outer coat bubbled as it were, and according with the general
appearance of the upper specimen.

It is perhaps an extraordinary circumstance that this
substance is not knqvvn to be attached to any rock^ and it

96

was once thought that only one or two specimens were to
be found in which it was attached. Mr. Day thought he
had one, which I now possess ; but I find that its supposed
great value now only consists in its being that identical spe-
cimen ; for, upon examining it particularly, I find it has
only the characters belonging to Iron Haematites, viz. that
of being soft enough to show the streak upon being
scratched, and which is red, whereas the Wood Tin should
not vary in the colour of the streak, if it can be scraped at
all ; also of becoming strongly magnetic when heated by
the blow-pipe upon charcoal, whereas Wood Tin scarcely
becomes magnetic, but is reduced to pure Tin. Klaproth
observes that this Ore contains more Tin than any other
Ore of the same Metal. It is found in Cornwall at St. Denis,
St. Columb, Alternon, &c. Spec. Grav. 7'29.
Analysis by Klaproth :

Tin

77'50

Oxygen .
Silex . •
Oxide of Iron

21-50

075
0-20

100-00

97

TAB. CCCL1II.

Common Argillaceous Slate, or Schist us.

Class 2. Earths. Order 2. Aggregate.
'Syn. Schistus. Linn. Syst. ed. 13. 3, 37.
Argillite. Kirw. 354.
Argile schisteuse. Haiiy, 4. 446.
Clay Slate. Jameson s Mineral. 1. 334,

The Slate commonly known as of a slate -grey colour is
found in many places in Great Britain, from Penzance in
Cornwall, through Wales and Westmoreland to the Calton
Hill in Scotland, where there are primitive rocks. Between
the different beds of Slate which lie in that direction are
beds of Lime-slate, as at Plymouth-Dock, where one side
is Slate and the other Limestone. Many parts of Scot-
land, and Wicklowin Ireland, abound with this substance,
and some afford much variety. Lord Penryn's, at Nan-
francon near Bangor, is quarried in large quantities for
London ; the dark grey and lighter sorts are used for slating
houses, and the less fissile ones serve for posts, or turning
into candlesticks and fanciful ornaments. Coat buttons
have been made of Slate, which proved very durable, and
often suited well with a dark, or light brown, or gray, or
mottled coat.

The front figure shows the durable Slate of Cornwall,
which is used in as thin and light plates as any. It has a
close, glossy, and nearly even appearance, and consists
chiefly of Chlorite with an intimate mixture of Ouartz,

J rv *

VOL. IV. I

98

upon which it depends for its durability, as it probably
does upon the different degrees of oxidization of the Iron
contained in it for the shades of colour. Killas and all the
schistose rocks in Cornwall are only different varieties of
this substance, depending upon the Talc, Ouartz, &c, be-
ing somewhat varied in quantity and texture ; which varia-
tion may easily be supposed innumerable, but which may
without much practice be recognized, although the word
Killas seems to have caused some confusion.

The lowest figure is Slate from Ingleton*, in Yorkshire \
and, like the Irish, Welsh, and Scotch Slates, often have
cubes of Pyrites in them.

The present specimen is one of that sort, and has a newly-
noticed substance on two sides of the Pyrites. We have
mentioned it to many friends, but can neither gain intelli-
gence about it, nor learn whether it is to be had in better
specimens. This is somewhat like Asbestus, the fibres
being at right angles with the Pyrites on two sides only.

The left hand is a specimen from Westmoreland.

* This place is famous for dendritical Pyrites on the Slate, forming- as it
were golden trees (see right hand figure).

99

TAB. CCCLIV.

It is not always that the substance which contains the
same ingredients as Slate, has the schistose fracture, as ap-
pears by its being turned in a lathe on some occasions. It
is rather remarkable that the Snake-Stone from Ayrshire is
a variety of the same substance as Slate, but is not generally
recognized to be such, on account of its possessing the slaty
fracture when in large pieces only, not showing it when
broken small. It is imported as a valuable and truly useful
article in many branches of manufacture; as for smooth-
ing copper, marble, Sec. For the latter it is formed into
the shape of mouldings, as in the upper figure. This sub-
stance is known in a great measure by its being so regularly
spotted, which, perhaps, has obtained it the appellation
of Snake-Stone, by which it is well known among work-
men. The light brown colour is analogous to the unspotted
part of a snake's skin. I have gathered nearly the same in
Cornwall, and some varieties are to be found, with the dark
spots beautifully relieved by satiny Talc of a looser tex-
ture : — see the under figure. I have specimens nearly like
it, but more indurated, from Keswick. The black spots
seem to be Hornblend, Chlorite, or Manganese.

In the upper specimen the black is generally of an equal
hardness and texture with the rest, or it would not suit the
workmen. When a stone from any quarry is found to have
the proper qualities, it becomes of much consequence, and
is a valuable article of commerce.

I 2

m

BE

101

TAB. CCCLV.

Siliceous Schistus, Hone- Stone, or Novacnlite.

Syn. Novaculite. Kirw. 1. 238.
Whet Slate. James. 1. 331.
Argile schisteuse novaculaire. Haiiy, 4. 448.

H one-Stone is generally considered as a foreign sub-
stance, said to be imported from Turkey ; and has hereto-
fore been always mentioned by authors as such. I can only
say that we have a substance so nearly resembling it in
England, that it may very fairly be considered as the same ;
and therefore I esteem the Hone a product of our own
country. It is more or less an attendant upon Slate. Its
colour is grey, light greenish grey, buff, and nearly white ;
its fracture splintery. I have it from the Carnarvonshire
hills, North Wales, (see the upper specimen) of a cream-co-
lour, like what is usually called Turkey Hone. Such is
much esteemed by the cutlers at Sheffield, and is sold in
proportion to its quality. A piece of about six inches in
length, fit for sharpening a razor, was thought so excellent
as to be worth a guinea. Many varieties of Hone-Stone
are found near Conistone, in Lancashire, and are sometimes
so prettily marked with dendrites as to have gained the ap-
pellation of Mocoa Stones*. The greenish Whetstone with

* Mocoa stones from Germany are perhaps coloured by* Bitumen, but
those from the East Indies by Manganese. In the first, the dendrites arc apt
to wear out, in the latter they are durable,

102

small dendrites, from thence, is figured behind, and the
upper middle figure is one with the larger dendrites ; this
nearly resembles the darker Turkey Hone, or, which is much
the same, the Carpenter's Oil-stone, but is more stained
and blotched. It is, of course, sometimes found without
the dendrites j but I figure it thus, to give one of its charac-
ters, and to exhibit a specimen of the sort of dendrites
which are supposed to be Manganese, and are sometimes
like stains upon the surface, as in the middle figure, and
sometimes run through the Stone in great variety, as in the
lack Jigure. Chorley Forest, in Lancashire, produces
a variety of Hones, or stones fit for sharpening tools,
which are called Chorley Hones. Indeed, there are vast
varieties of stones used by the cutlers, according to the
coarseness or fineness of the grain ; and their distinctions
are all so essential, that it becomes of much consequence
to know the sorts for different uses, and the trade in them
is of great importance both abroad and at home.

It is perhaps worthy of remark, that these stones may
be scraped with a knife, and give, generally, a light streak
like that of common Slate, although they will grind the
hard steel that will cut or scrape ihem. Schistose rocks
of many different compositions resemble wood. Perhaps,
from some of those usually called Turkey Hones resem-
bling wood, they have been thought to be petrified wood. I
am possessed of Schistose Rock from Devonshire, which
has been called Rotten- wood rock, from its resemblance to
rotten wood. I have, however, some petrified wood that
would nearly answer the purpose of a Hone, from Somer-
setshire, which shows the lateral fibre very distinctly, split-
ting with the usual longitudinal grain of the wood, and has
2 slaty aspect.

;5t=-_.

103

TAB. CCCLVL

S I L E X piceus.

Glassy Pitchstone.

Class 2. Earths. Order 1. Homogeneous.
Gen. 4. Silex. Spec. Pitchstone.

Syn. Pitchstone. Kino. 1. 292.
Pechstein. Emmerl. 1. 262.
Petrosilex resinite. Haity, 4. 3S6.

These Stones are so like Pitch in general, that no one
could mistake them, except when they vary in colour and
have a glassy appearance, as is sometimes the case. The
fracture in some fine specimens is large, concentric, sharp,
and conchoidal, in others more splintery. We figure one
of the latter, which includes Petuntse, or Feldspar, and al-
so has more or less of a glassy appearance. This, taken
in the whole, would be called Pitchstone Porphyry. It
came from Arran in Scotland, and contains Alkali. Hence
it nearly approaches common glass.

Quartz is so extremely likely to vary in its appearance,
especially when chemically combined with colorific or
other matter, that it may be considered as liable to as many
varieties as any other known substance. Thus it varies
from Calcedony or Agate, to Cachalong and the various
Opals : — see tab. 111. and also to Jasper, wax-like Horn-
stone, Flint, and even Pitchstone. Under the term Pitch-
stone may be included those siliceous stones which are fu-
sible and resemble glass, as they can scarcely be separated
but by fancied differences (as the usual appearance of Pitch

104

may be called either glassy or pitchy). There arc, however,
distinctions in sqme of them, which may be founded on
geological principles, as their being chiefly combined with
either Lime, Magnesia, or Alumine and Alkali, which often,
perhaps, depends upon the kind of rock they are formed
in : the colouring matter being either Bitumen, Manganese,
or Iron, in different states of oxygenization and quantity.

Pitch is of different textures, and has a fracture more or
less large or small, conchoida!, or glassy, and lighter or
darker in the splintery illinitions, depending on the degree
of heat to which it has been subjected. Pitchstone varies
as much j therefore, the present specimen may be called a
Pitchstone having a glassy appearance, with a rather small
conchoidal and sharp splintery fracture. As it includes
Feldspar, which spots it in some parts, it may be called
Pitchstone Porphyry. It is generally harder than glass, or
will scratch glass as Flint does. We are not sure that even
Bitumen enough may not be found hereafter, to mark its
analogy with Pitch very completely.

The present specimens were obtained from Arran, where
the substapce seems to be found in veins in a Porphyry
rock, and to pass into the more usual appearance of Pitch.
Jt has occasionally a basaltic aspect.

The visible and chemical characters of Obsidian agree so
closely with those of Pitchstone^ that they must surely be
considered as the same species.

K

105

TAB. CCCLVIL

Steatitic Pitchstonc.

I was favoured with the present specimen from a vale near
Clowance Park, in Cornwall, by Phil. Rashleigh, Esq.
The outer white parts are said to be Tungstate of Lime,
a very rare substance in Great Britain : there are also
some Asbestus and Ruby Copper about it. One great cu-
riosity attendant upon these substances is, that they natu-
rally contain an Alkali, which formerly used only to be pro-
cured from vegetables : the great discovery of the basis of
Potash and Soda, made by Mr. Davy, has thrown a great
light on these and other substances, as to their changes and
appearances, which we need no longer esteem positively
volcanic ; since the powerful agency of motion, with the at-
traction of these bases for oxygen, may give an effect which
we here see to be analogous to the power of a glass-house
furnace. These discoveries thus become of much more
consequence, as they lead towards the elucidation of what
we were before totally ignorant of.

The fracture is more or less conchoidal, like Pitch. It
is as hard as Quartz and nearly as brittle as Glass j and,

LI

107

TAB. CCCLVIII.

CUPRUM Sulphureum Arsenico-ferriferum.

Arsenico-ferriferous, or Grey Sulphur et of
Copper. Fahl-ore*

Class 3. Metals. Order 1. Homogeneous.

Gen. 12. Copper. Spec* 7» Arsenico-ferriferoussulphuret,

Syn. Gray Copper Ore. Kirw. 2. 146.
Fahlerz. Emmerl. 2. 238,
Cuivre gris. Haihj^ 3. 537.

Grey Copper has been found in several Mines in Corn-
wall. I have a neat little specimen in Tetraedrons from
Tavistock, in Devonshire, by favour of John Taylor, Esq.

The present very neat specimen came from North Wales,
and has many characters in common with the vitreous Cop-
per Ores found in Cornwall : it is, however, more brittle,
and differs in its crystallization. This Ore varies in its con-
tents, the specimens from Cornwall having only Copper,
Iron, and Sulphur ; while the foreign ones sometimes con-
tain Silver, Arsenic, and Antimony. Its neat and smooth
grey steel-like appearance makes it tolerably distinct. It is
more shining than the usual vitreous Ore in the fracture,
which is mostly small, conchoidal, and bluntish.

The present specimen has but little variation in external
colour, and, though easily scraped with a knife, is rather
faarder than the common vitreous Copper.

108

The right hand lower figure shows the regular tetrahedron^
or primitive crystal, and that on the left hand shows some
of its modifications, which are sometimes rather irregular.
A fragment of this specimen heated by the blowpipe was
found to be difficult of fusion : it gave out arsenical va-
pours, and was reduced to malleable Copper without showing
any signs of Lead. Spec. Grav. 4*4460 — 4*4560.

A specimen from Freyberg, according to Klaproth, was
found to contain :

Copper 48*

Sulphur 10*

Arsenic 14-

Silver • . 0*5

Iron 25*5

Loss 2*0

100-0

This analysis corresponds with the effect the blowpipe
'has upon the Welsh specimen.

109

TAB. CCCLIX.

CUPRUM sulphureum.

Subsulphuret of Copper, or Vitreous Copper Ore.

Class 3. Metals. Order l: Homogeneous.

Gen. 12. Cuprum. Spec. 4. Subsulphuret.

Syn. Vitreous Copper Ore. Kirw. 2. 144.
Kupferglanz. Emmerl. 2. 222.
Cuivre Sulfure. Hauy, 3. 55 L.

This is one of the richest Copper Ores, and is very abun-
dant in Cornwall. Its crystals usually partake of the hex-
aedral prism. Thus we have very short truncated hexaedral
pyramids placed upon very short six-sided columns, with
many varieties on the same specimen.

The present specimen at one end has these crystals mac*
kled, which I suspect has not been mentioned before : see .
the right hand figure, which consists of two crystals like the
middle one joined together. Some of the crystals on the
specimen approach the cross, like the left hand figure. I
have a good specimen, with many nearly such, but did not
think it necessary to give the whole. The one here figure^,
came from Cooks-Kitchen, Cornwall.

Ill

TAB. CCCLX.

This variety of vitreous Copper Ore is also found at Cooks-
Kitchen, in Cornwall, but is very rare. I have received it
among other favours from Mr. J. Taylor of Tavistock. It
is worthy of remark, that the crystals are of a large size
to what is usual, and the hexangular pyramids, which are
placed base to base, are more or less elongated : thus has
Nature sported with the crystallization, so as to prevent our
measuring with certainty the angle of incidence at their
mutual bases. Some of the crystals have the regular bevel-
lings of Haiiy, perhaps, not to be measured with certainty;
and some of the crystals have many lateral faces, so as to
give roundness, thus also to elude measure. The fracture
is mostly irregularly glassy, or minutely conchoidal. This
Ore is easily scraped or scratched with a knife to powder,
but is not brittle. The colour is iron-grey within, darker
on the outside : some specimens have the blue watch-
spring lustre and iridescence. Spec. Grav. 9 according to
Kirwan, 4.129.

By analysis it is found to contain :

Copper . . . 78-5

Iron • . . . 2-25

Sulphur • . . 10*5

Silica .... 0*75
The matrix is a mixed sulphuretted Oxide of Copper and
Iron* with Quartz, through which there runs a vein of the
vitreous Copper Ore with the crystals.

* The black Copper Ore of Kirwan, 2.143. Kupfer Schwartze of Werner.
This may, perhaps, serve as a sufficient specimen for this work.

This dusty or earthy ore generally accompanies the sulphurets, or other
copper ores. It is yellowish, reddish, or brownish black. Scarcely soils. Is
rather heavy. Contains about half its weight of copper ; but, from being ge-
nerally produced by the decomposition of the other ores of copper, it of course-
varies much.

113

TAB. CCCLXI.

HYDROGEN Bitumen.
Inspissated Bitumen, or Mineral Tar.

Class I. Combustibles. Order 1. Simple.
Gen. 1. Hydrogen. Spec. 2. Bitumen.

Syn. Mountain or Mineral Tar. Hatchett in Linn.
Trans. 4. 131.

This variety represents Tar so much as to be well entitled
to the appellation of Mineral Tar. Naphtha and Petroleum
lead equally to this and to the soft elastic Bitumens, branch-
ing off on one side to the elastic and on the other side to
the unelastic, of which this specimen is one. It is inflam-
mable, and in other respects, as to odour, &c, it is like
the others. It is found, apparently in the greatest abundance,
in the neighbourhood of Dumbarton, whence the present
specimen : it is otherwise very rare. It is remarkable that
the Iron-stones (Septaria) are the chief deposit of it. The
present specimen is part of one, and I have a Coal Septa-
rium not much unlike tab. 61, upper figure, that has this
soft substance in it. I have also a specimen among Quartz
and Yellow Copper Ore from Carrharac in Cornwall, with
some in a more brittle state, so as to take the impression of
the finger nail, but partly breaking at the same time with a
bright pitchy fracture. I have some also in Copper Ore
from Lancashire that unites the two; it is accompanied with
dark Limtetone.

VOL. IV. K

114

This substance is dark brown, has rather a greasy ap-
pearance, scarcely sticks to the fingers, and looks nearly
like the dark or dirty coom of cart-wheels, and as it were
lies about the divisions of the Septarium, or in the holes of
the other specimens. Smell, when a little heated, as usual
to the Mineral Bitumens ; by some thought agreeable,
though very different from Vegetable Tar. Breaks easily
with a rugged fracture; burns with much smoke; is not
soluble in Spirits of Wine.

Mineral Tar and Pitch are found in various states in the
islands of Trinidad and Barbadoes*, but I do not know
that any elastic Bitumens are found there.

* See Mr. Hatchett's admirable account in the Transactions of the Lin-
nean Society.

I

m

V;

115

TAB. CCCLXII.

SILEX quartzum arenaceum.
Siliceous Sand.

Class 2. Earths. Order 1. Homogeneous.
Gen. 4. Silex. Spec. U Quartz.

The Sandstone of Fontainbleau is well known to crystal-
lize in elegant groups of very neat rhombs, that represent
the inverse Carbonate of Lime, containing one third or
more of Carbonate of Lime, which appears to guide the for-
mation*. T have met with nothing like it as yet in Great
Britain. One of my sons, however, some six or eight
years since, brought me some flatted Cubes or right-angled
Crystals, which he found among sand said to come from
the neighbourhood of Ryegate. Some were partly ce-
mented by a little (Carbonate of Lime, and others were so
loose that they could scarcely be handled without breaking.
As I know of nothing similar, I represent it here as a ra-
rity in Great Britain. I also add a variety of Sand which
somewhat resembles the Roe of Fishes, or large-grained
Ketton-stone, or Pisolithus. It was brought me by Lady
Wilson, who found it at Charlton, and is likewise cemented
by some Carbonate of Lime. Something like it is also said
to be found at Fontainbleau.

The darker and irregular specimen is from Oxford, and

* Exotic Mineralogy, t. 1. See Proposal on the cover.
K 2

116

was taken out of the Ochre Pit. T have a large mass nearly
of this description, found in the mixed Lime and Sand
Stratum under the Thames at Rotherhithe, of which I do
not know that any one else has preserved a specimen. This
and others are more pr less cemented by Lime and Oxide
of Iron. We have, therefore, three remarkable formations
in the Sandy Stratum, which may prove highly instructive.

117

TAB- CCCLXIII.

A KG ILL A Topazius.
Topaz.

Class 2. Earths. Order 1. Homogeneous,

Gen. 1. Argil !a. Spec. 11. Topaz.

Syn. Occidental Topaz. Kirw. 1. 254.
Topaz. Emmerl. 1. 73.
Topaze. Hauy 9 2. 504.
Borax, gemma nobilis Topazius. Linn.

Topazes have been found in the island of Ceylon, the
Brazils, Bohemia, Saxony, Cornwall, &c. In Lesser Asia
a rose-red variety was discovered by our good friend Mr.
Hawkins before mentioned in this work ; and since that
they have been found in New Holland, and in Scotland.
The specimen figured is from Cairn-Gorum, and was lent
me by its kind possessor Thomas Allan, esq. It is the
more curious, as part of it is of a fine light blue colour*,
and part cinnamon-coloured, with a beautiful soft glowing
warmth ; and the disposition of the two colours seems al-
most to explain the nature of the crystallization. I thought
therefore it would be instructive to give a figure of the base
of the crystal, showing nearly the form the colours are dis-

* Topazes are of different colours, from deep wine yellow through reddish
yellows to greenish and rarely blueishi — also colourless and transparent.

118

posed in. See the left hand lower figure. The right liana
geometrical figure shows the faces of the crystal, the top
and bottom being primitive, with which the fracture agrees.
This figure is about the size of a crystal, from the same
place, in the possession of R. C. Fergusson, esq. which has
the same colours as the other, though more dilute. This is
perhaps peculiar to the Scotch Topazes, as may be verified
hereafter ; for they may prove to be more common than is
now expected. The people that gather them, often call the
Cairn-Gorum Quartz by the name of Topaz (being a stamp
of value) ; and they are sold indiscriminately. This cry-
stal, which bears the marks of many a violent storm on its
worn edges, has been broken through the primitive base
transversely to the column, and is fractured in the laminae,
showing the order of the prismatic colours very well; and by
pressure these colours are spread wider, which shows that
there is a great degree of elasticity in the laminae.

The geometrical figure is to show more distinctly the faces
that are in the principal figure, which is rather remarkable
for not having the faces so constantly opposite as they ge-
nerally are in Topazes. Between the large pentangular face
(72 of Haiiy) and the primitive apex, there is a parallel face,
not mentioned by Haiiy, and perhaps one opposite, but so
small that, as the crystal is rounded by attrition, we are
not sure it is there. At the lower corner is the triangular
face (c of Haiiy), on the nearest side, but I think not on the
opposite; but it is marked in the outline to show w 7 here it
would come. The two faces on each acute side of the
prism are primitive, on the top of which a want of increase
forms two faces (o, o, of Haiiy).

The larger four sides of the prism are the faces (/ ot
Haiiy). The figure within the outline shows the position
of the primitive faces and fracture. The obtuse angle of
the base is 124° 22' according to Haiiy.

The value of Topazes depends much on their colour and

119

lustre. It is supposed to be the hardest substance known,
excepting Diamond and Corundum. Their hardness, frac-
ture, and brilliancy may have confounded them with Dia-
monds ; and it is said that Saxon Topazes are heated to give
them a white transparency*, and are then actually sold for
Diamonds — it is even suspected by some that the reputed

Portuguese Diamond may be only a Topaz. Spec. Grav.
3-464—3*564.

The Saxon Topaz analysed by Vauquelin afforded him

Alumina

. 49

Silica

. 29

Fluoric Acid

. 20

Loss

2

100

gave

Alumina

. 47

Silica

. 28

Fluoric Acid

. 17

Oxide of Iron .

4

Loss

4

100

* 1 believe the camo i< done with some Diamonds. It is very usual with the
dark Cairn-Gorum Crystals. See Descr. tab. 102.

f 1

'4

121

TAB. CCCLX1V.

SILEX granatum.
Garnet, or Pyrope.

Class 2. Earths. Order 1 . Homogeneous.
Gen. 4. Silex. Spec. 26. Garnet.

Syn. Pyrope. Le grenat granuliforme de Boheme.
Haiiy, 2. 555.
Edler granat. Emmerl. 3. 246.

Mineralogists have made a division in Garnets, (if I
may so express myself,) by considering Pyrope as a distinct
species, when its only distinguishing character is its being
found in irregular pebbles and not crystallized. Lapidaries
long since used to consider Scotch Garnets of a peculiarly
brilliant lustre as different, under the particular appellation
of Scotch Garnets. I have some of these cut when in
fashion about thirty years since, and my friends have sent
me some in the rock under the name of Pyrope. It is per-
haps one of the most striking examples of nice discrimina-
tion that may ever happen : — these may be distinguished by
the Scotch Pyrope having the lustre inclining to fine red,
and the other to orange* ; and it should seem that they can
scarcely be distinguished when asunder.

Dr. Babington was so good as to favour me with the Py-
ope from Hungary. It is remarkable that it should never

* See red and orange in my Elucidation of Colours,

122

he found crystallized, which is one of the specific cha-
racters.

Our substance is as remarkable for being rather particular
in the crystal, being the proper Garnet Dodecaedron with
bevillings on each side of the edges, which is not usual in
common Garnets. See the right hand figure. This is no
less remarkable for some being truncated at those solid an-
gles, or alternate corners, where three edges meet, I believe
not before observed. If analysis should show any material
difference,' this will properly constitute a new species.
The crystals are in a gangue of Quartz more or less stained
with Oxide of Iron, part of it having a dingey greasy aspect.
The specimen was sent me from Ely, Fifeshire. It is said
that the Pyrope is found in the sand on the sea-shore near
the same place, and probably derived from the neighbouring
rock. — Might not loosened specimens of this be found on
the shore worn so as to obliterate the appearance of having
been crystallized ? and may it not also happen so in general
with those of Bohemia ?

133

TAP>. CCCLXV.

A N T 1 M 0 N 1 U M sulphureum.
Sulphur et of Antimony.

Class 3. Metals. Order 1.

Gen. 2. Antimony. Spec. 3. Sulphuret.
Div. 1. Crystallized.

Syn. Sulphurated Antimony. Kiriv. 2. 246.

Grau-spiess-glanzerz. Emmerl. 2. 468.

Antimoine sulfure. Hauy, 4. 264.

In Cornwall is found this stellated and spicular variety of
Sulphuret of Antimony. It seems to have the fracture
which is attributed to it by most authors, and is likely to
belong, as to its crystallization, to the geometrical figure be-
neath. Tt is curiously interspersed with small rhombic
crystals of Carbonate of Lime. This species is sometimes
of a fine polished steel lustre, and sometimes beautifully
iridescent. It may easily be scraped with a knife. The
powder is grey. It is easily fusible, wholly evaporating in
white funics.

125

TAB. CCCLXVI.

FERRUM sulphureum.

Sulplmret of Iron.

Class. 3. Metals. Ord. 1.
Gen. 8. Iron. Spec. 5. Sulphuret.

Biv. 1. Crystallized.

This singular formation of Pyrites, although of old in my
collection, is, I believe, new in description. Crystallo-
graphers say very little of the concave or convex rounding
of crystals of any sort, although it is often a strong charac-
teristic of some substances, especially the convex, as in the
Diamond : — Crystallography, part 2d, and Galaena, tab. 131
of this work, &c. The concave is, however, much more
rare : indeed the appearance is so extraordinary, that it has
been looked at more with an eye of wonder than investiga-
tion. The present specimens are examples of this concave
formation, and of the tarnish and iridescence which partly
disguise substances. They are nearly the same within,
although the smallest is so light- coloured outside, and has
a yellow, red, and blue iridescence ; and the other nearly a
fair yellow metallic tarnish. This latter specimen also shows
the convex formation, which is so great a contrast to the
former that it is altogether a wonderful group, whether
caused by the solvent or quantity of material attracted for
aggregation. It seems to be an accumulated repetition of
this formation that represents the Cockscomb of the fol-
lowing table. We have, however, still some very valuable
and extraordinary specimens that primarily lead to this pe-
culiarity, of which we shall be happy to make observation,
as they are truly instructive.

126

TAB. CCCLXVII.

Cockscomb Pyrites.

I believe this odd variety is peculiar lo England. Kirwan
(1st edit.) speaks of it as crystallized in small cubes or py-
ramids, united to a common basis " like cockscomb.''
Dr. Babington and some others mention Cockscomb Py-
rites, but some of our late mineralogical authors take no
notice at all of it. It is said to be. rare, excepting in Derby-
shire ; and as it is often very liable to decomposition, many
cabinets that once possessed it are now without it. Mrs.
Gent of Devizes was so good as to offer me the use of a
finer specimen, that is to say, a specimen with larger
cockscomb crystallizations. Both that and mine arc pro-
bably in a state of slow decomposition, for they are dullish,
and have a sulphureous scent, I suppose on account of the
Sulphur passing from them. The smoother cubical pyrites
and the striated have been considered by some as distinct
species, because one is more apt to decompose and fall to
pieces, as these and most others often do : this is therefore
scarcely a sufficient distinguishing character ; and I have
most varieties in the changes by oxidizement, from the com-
mon brown to the red oxide> and I have British and Irish
specimens in cubes, both smooth and striated, resembling
those from the West Indies called Sargestum (about which
I have had many inquirers) ; and I think, by various speci-
mens which I possess of Oxidized Iron, that Pyrites under
certain circumstances loses the Sulphur and becomes a solid
red Oxide. The present specimen is on a gangue of Car-
bonate of Lime with some metastatic Crystals more or less
stained or coloured by the red Oxides. Thus they change
by degrees to distinct species at each extremity. This is
perhaps a good example to show the difficulty of arrange-
ment, and the infinite varieties ; and that we should be cau-
tious of indulging too much in little distinctions.

127

TAB. CCCLXVIII.
¥ E R R U M quartzosuni.
Siliceous Iron-Stone.

Class 3. Metals. Order 3. Mixed.

Many places afford Iron-stones, Geods, &c. See De-
scriptions and Plates 106 and 107 *• The present specimen
is from under the Thames at Rotherhithe, where the Tun-
nel is perforated, in a mixture of Sand, Sandy Lime, &c.
It is remarkable for its branching, and in some specimens
so much so as to represent the more entangled roots of trees.
It is internally of a raw brown umber colour, nearly compact
appearance, and may be scratched with a pin, giving a
whitish streak : externally more or less rugged, with Lime
and Sand attached to it. I have only one instance of its
being found elsewhere, and that is a larger specimen in the
possession of Mr. Smith, who is so well known to be con-
versant with most of the Strata of this Island, who found it
in Wiltshire. The Iron in this specimen is in a low state
of oxidizement, and is intimately combined with Silex and
other earthy matter, as with a little heat it becomes mag-
netic. Some of my specimens are the more extraordinary
for having little Geods about the size of hazel-nuts, with

* I omitted one of the os;«al terms for Iron-Stones, which is Geods. The
term seems to be original with Sir John Mill in his History of Fossils, page
541, where he describes them as "cruslated ferruginous bodies, holding loose
earthy or arenaceous matter." He has made distinctions regarding more
solid coated varieties, Sec. as Hetropyra, Empherepyra, &c.

128

a coat or outward crust nearly the colour of the shell of those
nuts, and an ochre resembling Roman ochre, more or less loose
within them. Thus we have an use for the term or division
Imitative, from the resemblance of these to the branches of
trees and nuts. In many instances Nature's works are so
extraordinary in these productions as to elude the nicest
discernment, and teach us that much experience is necessary
to prevent error.

129

TAB. CCCLXIX.

CALX carBonata.

Carbonate of Lime.

Liu. 1. Crystallized.

Carbonate of Lime is so abundant in varieties and mo-
difications of its crystals, that we shall select only such
specimens as show something peculiar or instructive. Ia
the present instance we exhibit it with longer prisms than
usual, which help to give it the aspect of Quartz, which is
so common with a longish prism. Some specimens, but
such are somewhat rare, are not far inferior in lustre and
transparency to Quartz, but, like Diamonds and other dia-
phanous brilliant subjects, would be best understood by
comparison. Perhaps the brightest Carbonate of Lime
would be, in comparison to Quartz, as cut Paste is to Dia-
monds ; so that even the most experienced must try the
coldness or hardness, to help his judgement. The first
method would not hurt the Paste or Carbonate of Lime,
but the latter would damage them ; and specimens have
now and then been hurt by trial. We have, however, the
form of the pyramid to judge by; for Carbonate of Lime
never has been found with the obtuse equiangular six-sided
pyramid of Quartz, or representing any of the numerous
varieties of it: — thus the structure points out a distinction,
which, when understood, is discerned in an instant. The

VOL. IV. L

130

present figure, therefore, exhibits not only a rare specimen
or' Carbonate of Lime, but some varieties in the facets of
the pyramids. The upper figure is a small group with
pointed endings. The lower figure has the same faces with
lateral additions, and one is terminated at both ends. I have
added parts of two other varieties underneath, which occa-
sionally form groups. The upper right hand geometrical
outline shows one end of a crystal with a narrow face,
which is placed upon the acute edge of the pyramid. The
next outline beneath exhibits narrow faces on the terminal
edges of the prism, with a minute truncation upon the
acute angle, making three additional facets to each solid
angle: the obtuse end contains three of the primitive faces.
I have a group to correspond with the faces of the column,
alternating narrow at one end and broader at the other.
The right hand figure has an equiangular pyramid with a
truncated apex, nearly like Haiiy's fig. 32. This is rare :
it is from Derbyshire.

131

TAB. CCCLXX.

CALX carbonata.
Carbonate of Lime.

Div. 1. Crystallized.
Syn. Chaux carbonatee contractee. Haiiy, 2. 143.

A rare modification of Carbonate of Lime from Derby-
shire. The faces of the column being alternately broader
and narrower at the ends would, if extended, make an
acute rhomb, formed by a slight deviation from the law by
which the regular hexhaedral prism is produced. The apex
is formed by three faces corresponding with those of the
equiaxed rhomb, tab. 13 and 128, rendered pentagonal, and
contracted as it were into narrow facets, by the broader
ends of the columnar faces which approach the axis in the
direction of the edges of the rhomb; whence Hauy's name.
It is generally found more or less covered with a brown
crust, and has a roughish aspect given it by a mixture of
earthy Oxide of Iron.

The lower figure is less acute, and has also the equiaxed
termination : this also is rare, and is coloured a little.
Both are upon tabular Sulphate of Barytes.

L 2

1S3

TAB. CCCLXXI.

S I L E X Idocrasis.

Idocrase, or Vesuvia?i Garnet.

Class 2. Earths. Order 1. Homogeneous.
Gen. 4. Silex. Spec. Idocrasis.

Syn. Hyacinthe var. 3 to 8. De Lisle, 2. 291.
Vesuvian. EmmerL 3. 314.
Idocrase. Haity, 2. 574.

It is found pretty abundantly in a rock chiefly composed
of Mica, Hornblend and Garnet, on Mount Somma. The
present specimen was found in the county of Donegal in
Ireland, in what has commonly been called the Garnet
Rock, which is usually gathered in fragments for the sake
of the Garnet, for which this was sent to me ; and is curi-
ous on account of its colour. The rock is composed of
Phosphate of Lime, large-grained primitive gray Lime-
stone, Quartz, in some parts coloured green by Phosphate
of Lime*, and Garnet, among which is the Idocrase or
Vesuvian of some authors, because it was first known as
coming from that neighbourhood. This substance is recog-
nised in the specimen, by its prismatic structure and rather
darker colour, although lighter than usual : the Garnet is

* There are about the specimens several minute crystals of Phosphate of
Lime of a green colour, that bear some resemblance to Beryl.

134

irregular, somewhat more salmon-coloured, and lighter; the
Phosphate of Lime nearly white, and the gray at the bot-
tom is the coarse-grained Limestone of the county, which
is generally considered as primitive. The whole rock is cer-
tainly a curiosity, if considered in a geological point of view.

The small upper specimen has the Idocrase of the more
usual darker and shining greenish brown, and the Garnet
is crystallized; which assists in identifying it.

The crystal of the Idocrase is a rectangular four- sided
prism, with the lateral planes streaked and the edges most
commonly truncated. It is without its termination in my
specimen; but Haiiy exhibits a great variety of faces upon
the short or obtuse pyramidal apex. It has a rcsino-vitreous
appearance with very little transparency. It is hard enough
to scratch glass. Its specific gravity is from 3/0882 to
3-409. Melts with borax into a yellowish glass which ap-
pears red while hot.

Analysis of Idocrase, from Mount Somma.

Alumine . . 16-25 . . 22-25
Silica . . . 42-00 . . 35-50
Lime . . . 34-00 . . 33-00
Oxide of Iron . 5*50 . . 7«50
Oxide of Manganese . . 0-25

Loss . . . 2-25 . . 1-50
Thus we add another substance to British Mineralogy.
The specimens were sent, some time since, by Dr. Scott
of Dublin, without determining it. I say no more on this
substance at present, hoping some time or other to see
more perfect crystals, with less confused fracture and ter-
minations, and also of the Beryl-like Phosphate of Lime.

I

135

TAB. CCCLXXII

CALX phosphata.
Phosphate of Lime with Garnets.

Div. 2. Imitative, (fibrous.)

This substance, which I have received from the neigh-
bourhood of Aberdeen, by favour of several friends, as a
phosphorescent Granite, appears to be a fibrous Phosphate
of Lime with Garnets, either decomposing, or not so per-
fectly formed as usual, but showing plainly the Garnet do-
decaedron more or less interrupted by the Phosphate of
Lime. Mr. Jackson, F.L. S., found some at Tierbagger
and Cultcrby, on the Dee side, near Aberdeen, and it is
certainly a curious production, not mentioned in any
British or even foreign authors. If a fragment be placed
on a hot iron or poker, it has the blueish glowing phos-
phorescent appearance of some of the Fluors. The Gar-
nets in this rock are sometimes so small as to be almost in-
visible : sometimes they appear only in the form of irregular
blotches; but occasionally they are more regular and not
attached to the rock, but only fill up a dodecaedral hollow,
and have then the appearance of the lower figure, yet seem
to be much mixed with the substance of the rock. The
Phosphate of Lime is in small bundles of fibres closely
matted together, of a pale blueish green in the most com-
pact parts, but whiter and even brownish near the surface,
where it is in a decomposing state.

137

TAB. GCCLXXIII.
SILEX granatum.
Garnet.

Div. 1, Crystallized. Far. Trapezoidal.

Garnets in trapezoidal crystals are not so common as in
rhomboidal dodecaedrons and its modifications, for which
see tabs. 43, 44, 120 and 364. They, however, occur in
some variety, as to the perfection with which they crystal-
lize; their brilliancy, and additional number of facets.
Like the former, they are sometimes detached from the
rock, or easily separated. The best seem to be most usually
in the least decomposed Granites. The upper figure is an
irregular fragment of micaceous Granite, of which the red-
dish part is Feldspar; the whiter part, Quartz; and the
whitest, Mica. The Garnets are of a good colour, and
have a tolerably natural polish : some are rather compressed,
and some have a face or four-sided truncation upon the
apex of the four-sided pyramid. The lower middle figure
is representative of those in the gangue above. The left
hand lower figure is a larger and nearly regular one, of a
dull roughish aspect, found detached, or rather having
fallen out of a somewhat sandy rock. The other, which is
larger, showing the truncation, was sent me detached, with
some other favours from Scotland, by the Rev. James Dal-
ton, and the former ones are from the neighbourhood of
Aberdeen.

138

Garnets vary much in size. I have one, with which I
was favoured by Lady Wilson, from Scotland, above an
inch in diameter, and they are sometimes larger ; perhaps
they may be found equal to those from Fahlun in Sweden,
which I have seen very large ; and I have one, a rhomboi-
dal dodecaedron, nearly five inches in diameter.

These specimens, with their gangues, will be doubly
useful when we come to treat of the Rocks.

wm

139

TAB. CCCLXX1V.

FERRUM sulphureum.
Curving or Bending Pyrites*

Div. 2. Imitative,

Perhaps 1 could not show any thing more extraordinary
or, I believe, more rare in the system of Crystallization, than
the present specimen which I possess by favour of my
good friend Philip Rashleigh, Esq., of Menabilly, who
sent it to me in 1806, labelled from Carundale in Devon-
shire.

Pyrites is well known to form the Cube and Octaedron,
with their modifications, very neatly : see tabs. 29, 30,
99, &c, and to produce varieties from them, wedge-formed,
rounding, concave, and convex, cock's-comb-like, &c;
see tabs. 366 and 367; and to mix in somewhat cruciform
and other odd appearances. In the present instance the
Pyrites seems more like Sheet Metal cut into pieces,
as if with a pair of sheers, curving in various directions :
thus we have an appellation of st imitative " to recognise
it by ; which is very convenient in the present instance. I
do not know that curved crystallization has been at all
mentioned by any author. I should suppose, however, that
it depends upon the same laws of aggregation in this sub-
stance as the straight or rounded ; see vol. ii. p. 57: and
the rounded figure in tab. 131. Its state while depositing

140

from the solvent, and the solvent, may account for immense
variety. This, however, is a very rare example, identifying
a new kind of form, and bespeaking another source of
boundless variety. The crystals seem to be formed of plates
belonging to the cube and cubo-octaedron, passing in a
more or less continued line of elongation, forming a sort of
wall-like appearance in various directions, and may perhaps
be compared to a tall weak wall on an irregular foundation,
bending before it was hardened by drying. The crystalli-
zation of Pearl -spar, tab. 1Q, lower Jigure, which curves*
seems governed by a different law : the molecules seem to
slip while depositing; and the Sulphate of Lime, tab. 68,
seems to bend from an elastic property.

141

TAB. CCCLXXV.

FERRUM oxygenizatum.
Oxide of Iron.

Class 3. Metals. Order 1. Homogeneous.

Gen. Iron. Spec. 3. Oxide.

Div. 2. Imitative.

The present is not only a new but an instructive specimen.
The crystals are secondary, but so perfectly distinct to every
observer, that their derivation is truly evident. The grand
vicissitudes and changes continually going on, even out of
our sight, become in this instance very evident : — were the
operations carrying on in our sight, we could not be more
certain of them. Hoematitic Iron, see tab. 56, is shown
in this specimen, forming the concentric radii, in coats
one over another, having lain over metastatic crystals of
Carbonate of Lime; which being decayed, their place was
filled up by a fresh supply of Oxide of Iron, with such ex-
actness that the least attention to crystallization discovers
the process. The moulding or coating in this manner is
so sharp and accurate, that it may lead to a means of im-
proving in such arts, especially as it is evidently a wet pro-
cess, although it possesses so much the resemblance of fu-
sion, as to have been actually thought so by some; but we
herein see how the two processes resemble each other when
completed.

■ m

142

Three different states of Oxide of Iron are visible in this;
viz. the black-brown, the red, and the Roman Ochre; and
I conceive an indefinite number of Oxides may be formed
by the blending of these : nor do I think Iron is capable of
taking oxygen from water, &c, in these different degrees
which colour seems to represent; but when blueish or pur-
plish, or any variety exists, it may depend upon Carbonic
Acid, Hydrogen, Phosphorus, Manganese, &c, which
may be known by their external appearance.

143

TAB. CCCLXXVI.

CUPRU M nativum.
'Native Copper.

Class 3. Metals. Order I. Homogeneous.
Gen. Copper. Spec. I. Native.
Div. 2. Imitative (wire-like.)

Perhaps this formation would never have been expected in
Native Copper by the tyro in Mineralogy ; and it is indeed
very scarce. The rounding branches irregularly disposed,
inosculating with their bluntish terminations and rugged
rusty appearances, might be taken at first sight for a number
of pieces of Iron wire aggregating so confusedly by means
of rust : however, in colour it approaches to Copper, and
may by scraping be easily distinguished, having the softness
and red metallic lustre. It is rather remarkable, that the
branches, if I may so [call them, are sometimes so much
coalesced as to join apparently in a continuous manner; at
others they seem attached, as if pressed one against another
and stuck together ; and some parts of the sides and ends
terminate as if they once had been joined to others, some
being blunt and roundish, and others having a small con-
cave disk.

I have placed another branched specimen, having the
branches six-sided and somewhat irregularly cut, resembling
an endeavour to do it with a knife, and so are somewhat

144

scalloped, partly concave and generally rather flattish, with
two sides broader than the rest ; see the right hand magni-
fied figure at the bottom.

I have placed another peculiar ramification at the bottom
on the left hand, showing more of the nature of structure
depending on the order of the crystallization, more or less
zigzag or feathered, which is shown more distinctly in the
magnified figure. The whole are very small, but indicate
the rhomb, tab. 216, and the dodecaedron, tab. 25, which
are almost recognisable : the rhombic accumulation is
pretty evident, and the angles of the zigzag appearance are
the corners of the rhombs. Moss Copper generally belongs
to this variety.

The specimens are from Cornwall, but the upper one is
the most rare : such are much valued.

145

TAB. CCCLXXVII.

SILEX quartzum, var. opalinum.
Opal.

I have given (Brit. Min. Ill) a figure and description
of the Precious Opal of Cornwall. I now show a variety
from Sandy Brag, brought from thence by Humphry
Davy, Esq. of high chemical celebrity. Opals have been
divided with some difficulty into several kinds; as The
Precious Opal, The Common Opal, Semi- or Halb-Opal,
and Wood Opal. The good and bad might have been
sufficient distinctions, as the several kinds run into each
other. The three first arrange according to their good-
ness ; the Precious Opal having a pearly brilliancy with a
fine soft display of most of the prismatic colours, and a
brilliant lustre peculiar to itself: the Common Opal has
less of this lustre; and the Halb-Opal borders on it so feebly
as to be considered as only partly an Opal : the Wood Opal
may have all these varieties, but is infiltrated into the re-
mains of wood retaining its structure. These distinctions
therefore do not all belong to the substance, and become
incorrect, or mislead. The present specimens are remark-
able : the upper o?ie 9 for a fine somewhat resinous appear-
ance, from a light dull greenish yellow to a resin brown,
with a fiery or orange yellow sparkling splendency reflected
as the light passes among the flaws.

The upper specimen is in a sort of decomposing Porphyry,
spotted and veined with resin -like Opal mostly dull in colour.
The lower figure has something of the appearance of light

VOL. IV. m

146

Burgundy Pitch, and is such as is often found in the ligni-
form state. I have an example in a foreign specimen
mingled with Pitch -stone.

Opals are chiefly Silex with from 5 to 10 percent, of Water,
and, under certain circumstances, are so operated upon,
that moisture and change of temperature more or less sud-
den seem to cause the various appearances ; and those that
become degraded below the Precious, are less and less pure
with various adulterations. Generally found in more or
less perfect Porphyry.

Analysis of the Opals :

Precious Opal. Common Opal. Semi-Opal.
Silica - - 90* - - 93*50 - - 43-50

Oxide of Iron — - - 1-00 - - 47*00

Water - - 10- - - 5-00 - - 7*50

Loss - — - - 50- - '2-00

100- 100*00 100 00

/

147

TAB. CCCLXXVIIL

ARGILLA electrica.
Stellated Tourmaline*

The different appearances that various substances assume
is the greatest stumbling-block in Mineralogy : it becomes
therefore necessary to learn them; and although forms under
the same terms may belong to various substances, they are
nevertheless often characteristic of particular species. The
present variety, although not common, is pretty well known
among the Cornish miners, who call it Cockle, which is
generally recognised as Schorl or Tourmaline by mineralo-
gists. See tab. 209 and 210. We may find specimens that;
lead from the more crystallized form of those of the fila-
mentose structure through a great variety of arrangement
to the present stellated one, where the crystals shoot as it
were from a centre, are thin, and interrupted in their forms
by pressing among each other ; so that externally we guess
at them from a similarity in appearance to those of a more
conspicuous size, generally angular, and mostly shining and
longitudinally striated on all sides. If experience does not
determine them to our satisfaction in this, we must proceed
to hardness, electricity, 8cc, to find their correspondence.

Our specimen is rather remarkable, being in a gangue
chiefly composed of Mica. I have a specimen from Aber-
deen nearly like it ; but the Schorl is chiefly imbedded in
Quartz, and a mass of Mica attached to the specimen has
only a few scattered bits in it.

M 2

P2

149

TAB. CCCLXXIX.

S I L E X f Vagilis.
Brush-like Actinolite.

T. his curious and remarkable variety is not uncommon in
some parts of Scotland, and further north. Its laminated
structure and softness will pretty readily distinguish it from
Schorl, which it has been taken for. The upper figure
represents the opposite side of a piece not much unlike the
lower specimen, and is composed almost wholly of Actino-
lite lying in confusedly parallel order, with an oblique
whitish streak looking like a vein : the rest is mingled with
dull and darkish greens : one end shows its scopiform ap-
pearance : on the other side it is more crowded than in the
specimen beloiv, which is more schistose, composed of light
gray fine silvery Mica, relieving the curved brush-like lines^
formed by the somewhat twisted bundles of actinolite, which
are rather dull greenish black on the surface, but shining on
the sides, and nearly resemble the end fracture of the tipper
specimen. I received this and some other interesting spe-
cimens from the north of Scotland, by favour of my good
friend James Brodie, Esq. formerly mentioned in this work.
It was gathered bv the Rev. Patrick Forbes of Boharm in
Scotland,

r /

7

imm

151

TAB. CCCLXXX.

BARYTES sulphata.
Sulphate of Barytes.

Div. 1. Crystallized.

This figure leads from nearly the primitive thickish rhom-
boidal prism to the flatter plated crystals, which are piled
by the side of each other upon one of their most acute edges,
(see tab. 70,) consequently giving it a very different appear-
ance from the right-angled plates more usually seen, as in
tab. 72, the edges of which are parallel to the diagonals.
The crystals upon this specimen are mostly truncated upon
the acute solid angles, the truncations forming little trian-
gular facets ; and they are all so deeply truncated at the
obtuse solid angles, that the truncations meet. Tab. 70,
bottom figure, shows one of these faces 5 and Tab. 95 ex-
hibits both.

This specimen came from Dufton. It is convenient here,
as it partly leads to those flatted primitive forms that stand
on the acute edges and are often very thin, without any de-
crement on the angles, but occasionally passing by minute
degrees towards an elliptical form, produced as it were by
being placed by the side of each other when forming, but
slipping or falling a little out of the parallel with those above
or below. This sometimes seems the cause of the curved-
like appearance which happens in Sulphate of Barytes like
that of Pearl-spar, tab. 19; more particularly when the latter
is a flatter variety. The weight and pearly lustre will, how-
ever, most generally distinguish them* The next figure
partakes of this appearance.

1 1

Mi

153

TAB. CCCLXXXL

BARYTES sulphata.
Sulphate of Barytes.

Div. 2. Imitative, Stalactitical.

These crystals of Sulphate of Barytes are placed upon
their acute edges; they are for the most part extremely
flat, so that the column is as it were lost in flatness,
and the form is in some parts less easily understood, as
they are crowded very much, and strangely grouped into
hanging and curving forms, and each individual crystal is a
little rounded. The present specimen is, I believe, as rare as
it is curious, as we could less expect a heavy substance
like this to have such an appearance among the groups.
Some have an apt resemblance to a parcel of petals, giving
the appearance of a corolla or flower. See the lower figure.

We need not wonder perhaps at any general appearance
of this substance, when we see how it sports here ; yet it is
necessary to know that it has many odd appearances which
might be attributed to something else.

TAB. CCCLXXXII.

Stalactitical Sulphate of Barytes, as far as we know,
has not been observed by any author. I have therefore
introduced it as one of the curiosities that was in Mr. Day's

154

collection. It is from Matlock in Derbyshire. It shows a
curious state of aggregation, crystallizing after solution,
running and dropping in very elegant and varied forms.

The crystals sometimes line the tubes and nearly fill them
in a concentric manner like the common calcareous stalac-
tites : the tubes are often nearly empty. The outsides of
the tubes are covered with somewhat globular aggregations
of sharp lenticular crystals, some of which have very much
the appearance of globular crystals.

4

155

TAB. CCCLXXXIII.

FERRUM sulphureum.
Sulphuret of Iron — Iron Pyrites.

Dlv. 1. Crystallized.

Plates 366 and 367 are curious examples of the crystalli-
zation of this substance. The present extraordinary speci-
men seems to elucidate somewhat of the origin of those
modifications from the cube. See the right hand lower figure.
Two of the horizontal edges at each end of the cube are
replaced by rounding faces of such extent that they meet
each other in a line, towards which the vertical faces are
enlarged at the same time that they become concave (see
ihe right hand figure) : three of these crystals are grouped
together to form ihe left hand figure, thus disguising the
cubic structure. These and various other intermediate forms,
depending upon such a process, are on the specimen, that is
to say, one independent crystal, another notched, or one
joined as it were by one of its concave sides to another or t wo
others, not more, with the mutual loss to each of a concave
face, forming a straight seam, while the other sides are more
or less concave or straight, same as represented in the figure y
with the strice of aggregation on the upper part, as I shall
call it for distinction sake; the whole appearing as if formed
from a centre into three w r edges. The crystals on this spe-
cimen are remarkable for their thickness, which much faci*
li tates the study of them : as they become thinner, they

156

generally group in greater numbers and with less regularity,
thus forming the Cock'scomb Pyrites above referred to in
tab. 366. The crystals are much elongated, and some of
them are joined by their convex faces, forming deeply fur-
rowed groups, not notched plates.

The gangue of this specimen is octaedral Galaena coated
by Cubic Fluor.

TAB. CCCLXXXIV.

This is a modification depending on the same laws of
aggregation as the last; but the notches are filled up by a
continuation of the striated faces : the crystals are much
compressed, and often very thin, having the appearance of
hexangular plates, three sides of which stick deep in the
gangue : they however terminate more or less solid in two
or three angles only, against each other, or in the more
massy part of the Pyrites. This Pyrites alternates two or
three times with the Quartz,

157

TAB, CCCLXXXV.

C ARBO bituminosus.
Plant-formed Coal.

Div. 2. Imitative.

No subject in Mineralogy is more deserving of the attention
of mankind, oris perhaps more instructive, than the forma-
tion of Coals ; whether it bespeaks the contrivance of a flood
as necessary for their formation, or proves that they are in
the great bulk, at least as far as we are allowed to penetrate,
dependent on principles passing through organization. Nor
is it the less curious, that while we have appeared so long
ignorant as to the nature of the subject thus returning to an
inorganized state, yet every day some fresh assistance meets
our inquiries, as we are allowed to improve them by an in-
dustrious research. The present specimens are proofs of
the eminent beauties constantly observable in the variations
of Nature; and while they show an analogy to our mo-
dern system, yet present us with Genera and Species so
foreign, thai we are at a loss for comparison. The front
specimen is the cast of a stem of some plant which is co-
vered with a very regular arrangement of squamae, such as
remain occasionally after the old leaves are fallen off as the
smaller branches advance. The squamae are very perfect in
appearance, and are arranged in spiral order; in some speci-
mens the spire winds to the right, and in others to the left ;
those on the right hand side of the specimen figured have an

158

embossed centre, and an apex somewhat thickened, and ap-
proaching the obtuse triangular scar that the leaves of many
plants leave after falling off, with the decurrent swelling
below. The nearest approach to this regular lozenge for-
mation is in the small branches of some species of pines,
Euphorbias or Proteae. From the larger flatted impressions
and the smaller branched ones, it should appear that this was
not a very small species of plant. I have a flattened im-
pression that is seven inches wide, and this specimen is
smaller than some others which I have, but was chosen for
its having the divided end, showing that the plant branched,
besides the sign of the two pith-like round holes, one for
each branch, remarkable for being on one side in these, as
well as in those not branching. The hollow is generally
longitudinally striated.

The other specimen shows a smaller branch, with some
remains of leaves which arc a little carinated, acute, in
length about twelve or sixteen times their breadth, and
swelling a little from their base.

These specimens are both Ironstone, upon which the
coaly remains of the plants are impressed. In the front
specimen, the Coal has the usual fracture, and is about the
tenth of an inch thick where the squamas are most distinct,
as one side has only little regular embossments, the squamae
being obliterated by scaling off or wearing; or perhaps they
were never so perfectly formed, on account of their being in
a position less fitted to preserve them: this ought to be
noticed, lest in some instances it should lead to mistake in
the species.

Other species of similar construction are found at Lord
Middleton's, Woollarton, near Nottingham. I jpave, among
other remarkable ones, some much branched, by favour of
Thomas Meade, Esq., from Poulton in Somersetshire.

TAB, CCCLXXXVI.

C A R B O bituminosus.

bituminous Coal, containing Animal Remains

Div. 3. Amorphous.

Coal is now much more universally understood to ori*
ginate from the vegetable decomposition than when I com-
menced this work, and my figures in tals. 187, 188, 189,
385, 8tc, appear to place it out of doubt. It however does
not exclude the probability of animals at the same time de-
positing their proportion of Hydrogen and Carbon in similar
circumstances of decomposition, underpressure, and caught
when more or less in full life and perfection, and fittest to
form the more perfect Coal. Animal remains, however, like
the vegetable, can in this instance be detected only by the
stronger parts that appertain to either: the latter by impres-
sions, casts, &c. in the more earthy substance that enveloped
them while their juices were infiltrating by means of
moisture and their own more volatile parts. The former is
somewhat more rarely detected in the coal formation; the
actual remains of the more, earthy parts> however, attending
their structure forming moulds, &x. Thus analogy teaches
us that the more volatile parts, like those of the plants, are
infiltrated into the Coal.

The present specimen, having the shells actually among
the Coal, is so presumptive a proof of this, that we have no
hesitation in considering it as a confirmation; and as we do

160

not often find the actual remains in the Coal formation, we
conceive it very proper to give a figure, especially as the
shells are in such perfection as to be known outwardly
nearly as well as if they were recent. As far as I could
detach the coaly matter, &c. from the inside of one, it
seemed to have no more hinge than My til us cygneus of
Linnaeus, which it greatly resembles, but it is a thicker
shell : it does not strictly accord with any modern one that
I know, I shall therefore call it Mytilus crassus. The shells
are composed of crystallized Carbonate of Lime, in some
parts rather transparent. The specimen has other Carbonate
of Lime in the crossings and small partings, with some
argillaceous Oxide of Iron. The coaly part is mostly bi-
tuminous, and has the fractures corresponding with it. It
appears to be found in large compressed layers, with innu-
merable quantities of shells of this sort only. They were
called petrified Oysters by the miners, who found them in a
stratum above the Cannel Coal near Wigan.

I at present know of no others so absolutely in Coal. The
usual Ironstone that accompanies Coal has many species
of shells, which however seem to accord with the Mya of
Linnaeus.

161

TAB. CCGLXXXVII.
SILEX quartzum, var. fibrosum.
Fibrous Quartz.

Div. 2. Imitative.

Sir Joseph Banks* the discoverer, and many others who
have been surprised at the regular pediment and archi-
tecture formed at Fin gall's Cave, now so well known,
would again be surprised, were they to see the present
specimen of the same dimensions. As a representation
on paper, however, only gives a diminished figure, this,
in that respect, only wants the idea of largeness to be
annexed to it to equal that in grandeur.

Here we see what may in common be termed coarsely
fibrous Quartz, the fibres lying in a vein in a Schistose
Rock stretched more or less regularly from one side to
the other, connecting the two by these filaments ; a very
curious circumstance, and little noticed before this in any
Mineralogical work.

Besides the instructive point in which the upper specimen
may be viewed, the picturesque structure which represents
a ruined Temple also points out a new and most natural
order for Architecture. The upper part represents a rude
and heightened pediment, with a sketch of radii placed be-
hind a bust 2 which is roughly but elegantly sculptured, as
if for a sign to point out to whom the building was dedi-
cated. The cornice is in a somewhat stalactitical form,
giving much effect by projecting forward so as to show the
stalactites partly in the shade beneath, which, in tolera-
ble order, hang lower and lower till a less projecting cor-
nice is as it were formed, with various openings, orna-
menting the space between like Attic windows elegantly
contrived of oval and other forms. Beneath this cornice
are the main columns in varied proportions, arranged so
as to admit light to the interior, and finishing by gradually
swelling into a sort of base on the lower cornice and on
some of the columns, giving a good hint for order.
There are some bright octaedral crystals of Pyrites, point-
ing out judicious places for lamps.

* Who first made known the description of Fingall's Cave, and furnished
Pennant with the account.

VOL. IV, . N

HI

i

162

TAB. CCCLXXXVIIL
S I L E X quartzum.
Stri/ied Flints.

Div, 3. Amorphous.

Scotch Pebbles and Agates are most commonly known
in beautiful variety of concentric circles or laminae, and
have been in high estimation in jewellery, and still conti-
nue so. See tab. 160. Striped Flints are less known; al-
though not very uncommon, yet more rare than the
above, especially when the stripes are in circles, or con-
centric ; and they are only valuable for information, and
have in general less variety of colours and probably of
substance.

The upper specimen is from King's Weston, near Bristol,
and consists of more or less condensed Flint ; the denser
parts are the darkest, and the lighter more or less porous,
and occasionally coloured of an ochraceous hue. The
present specimen is remarkable for having a hollow cen-
tre, and the circles being so extensive that when broken
externally it of course appears as if there were many cir-
cles and centres. Flints of this nature and of a larger
size are found at Woodford in Essex.

The lower specimens are such as are found in the Gravel
near the Chalk Pits at Charlton, Plumsted, &c. These
are sometimes apparently parts of the larger sort, and are
more or less rounded by attrition, consequently showing
a later time than that of their formation for being depo-
sited in their present situation.

The stripes in these instances seem to depend upon a
deposition of the parts while supported by Marie or
Clayey Rocks, and not upon laminae falling like strata,
one part imposed upon the other : — the lower pebbles
were thought to be of the latter construction.

163

TAB. CCCLXXXIX.

S I L E X electricus.
Pointed Schorle.

Among the many forms that this substance assumes, and
not rarely, is the present; but it has not yet been described,
to my knowledge. It is composed of elongated prisms, a
smaller or greater number of which commencing at a point,
often diverge to great lengths, thickening more or less regu-
larly, as figured. I have them mostly six-sided, with some
of the angles here and there truncated longitudinally, so that
some have as many as twelve sides, giving the appearance of
a peg cut in angles and left without being rounded. I ex-
pect they are often of great length : what I have are only
about three inches long (sent me by the Rev. Patrick Forbes
lately mentioned), but these have no terminations. They
sometimes, however, end abruptly, as thehollowimpressions
show: they sometimes also have a transverse crack, which
is filled up with Quartz. Indeed it does not appear to me
that any one has yet made a research for the purpose of in-
vestigating to what length Schorle may shoot or lengthen :
perhaps this may be a hint towards some attempt of the
kind; which, however, is the more difficult as it is so frequent-
ly among Quartz in the hard Granite Rocks : when, however,
it is found among the more micaceous parts of it in veins,
it may be better traced, as in such situations it is often very
long, but perhaps seldom so perfect.

I was favoured with the upper specimen by the Earl of
Seaforth, from the neighbourhood of Portsoy in Banffshire.
In it the Schorle is passing through or among Felspar or
Kaolin and Quartz, leaving its impression where it has be-
come detached, which is often the case, as in some parts it

164

is almost loose, with Mica interposing between it and the
Ouartz. I add the lower specimen as a remarkable variety
among shattered Ouartz, diverging and divaricating in fas-
ciculated prisms almost approaching to spiculce; the prin-
cipal Quartz fracture being on one side or at right angles
with them or nearly so, as if formed in another direction.
This is from Aberdeen.

tab. cccxc.

When I was at the Logan Rock, well known in Cornwall^
I gathered this specimen within a few yards of it out of a
very large solid massy vein of Ouartz. It ran some length
into the Quartz, but owing to my want of time and tools I
could not ascertain how far. This specimen is of a close
hard texture, and finely polished, which approaches what
may by some be called the Tourmaline variety; it has a
slight greenish hue when viewed so as to transmit the light 5
and is more or less covered with the prismatic iridescence.

w7.

3 m

165

TAB. CCCXCI.

S I L E X Mica.
Brown and Black Mica.

This substance may be found of almost all colours, except
blue; at least there have not yet been observed any speci-
mens of that colour. The darkish Irown variety, figured at
the upper part of the plate, is not uncommon in small specks
or specimens in Granite, but rather more rare of a larger
size: the group is not as usual convenient for dividing into
plates, but is seemingly a congeries of scalv crystals ar-
ranging in a peculiar angular manner, sometimes according
with the angles of the primitive rhomb, meeting and min-
gling so as to become quite zigzag, while the accumulated
planes are diverging from different centres in confused order.
Its colour gives it rather the appearance of thin horn, but
it has a more glassy lustre.

The lower specimen is rather rare, being of a true shining
black, i. e. black without any mixture of brownish, blueish,
or any other colour : it has a more glassy lustre than the
upper specimen. The congeries of plates on one side of the
specimen are small and on the other larger, more continu-
ous, partly undulated, and altogether less orderly, and not re-
gularly enough grouped to need particularizing.

Common brown Mica of the shops is often two feet or
more square, and when used very thin for microscopes ap-
pears nearly colourless.

3 ,1 0

16?

TAB. CCCXCIL

PLUMBUM sulphureum.
Slickensides Galama.

Div. 2. Imitative.
Syn. Spicular compact Lead Glance. Jameson 2. 355.
Compact Galasna. Klrw. 2. 21 S.
Slickensides. Bab. J 70.
Plomb sulfure compacte. Hauy 3. 461.

This variety of Galaena, rare in any country but England,
is found chiefly at Castleton in Derbyshire, and I have some
specimens marked Ecton Mine, which is partly in Stafford-
shire. It appears to be the common Galaena, but, by a
certain slip of two faces as it were of a separated mass of
rock, is pressed into a finely granulated compact appearance,
quite losing the regular cubic fracture, otherwise usual to
Galaena, and which so essentially distinguishes it from
most other substances. Sometimes this is rather massy in
the interior part of the specimen, near or quite adjacent to
the polished face, caused probably by the broken ends of
strata slipping and pressing against each other. It may be
on the face of mixed rocks, on Fluor, Quartz, and Sulphate
of Barytes. It is said to be dangerous sport to the miners
when they meet with it unexpectedly, as it is easily detached
with a sudden explosion, and is thrown with such consider-
able force that it has even been fatal to those that are within
iu range of action; but when, as by experience, they have

163

learnt to discover, by tbe sounding* of their tools against the
spot, that the next stroke may detach the slickensides, they
stand beneath, if the situation allows, and, advising their
friends to arrange themselves in safety, spring the mine as it
were in triumph. I presume that the compressed air, allowed
relief from a space so broad and suddenly coming into con-
tact with the common air, causes the noise, and the expan-
sion impels the stones to a proportionate distance, and frag-
ments fly afar over the operator's head, who has a reasonable
cause to triumph, as his knowledge has taught him to make
sport with safety where he might have suffered by ignorance.

The specimen figured in the front of the plate is from
Ecton Mine, where so many brilliant coloured and variegated
specimens of Pyrites occur; and this is not a common va-
riety, because it partakes of the splendid prismatic colours
added to the highly polished surface. The piece figured be-
hind is more usual, and at first sight very much resembles
the Free-stone of a chimney when shining with common
Black Lead or Plumbago, which sometimes by means of
smoke has the iridescent or prismatic colours, but in this
it does not resemble it. This specimen has Mineral Pitch
and Pyrites about it in veins.

Other substances are liable to be polished in the same
manner, and apparently from the same causes.

m^mam

169

TAB. CCCXCIII.

SI LEX quartzum, stellatum.
Radiating or Stellated Quart -.

Div. 2. Imitative.

This has long been esteemed as curious, and is perhaps
nearly as remarkable as the Corsican Granite*; which, al-
though differing somewhat in the contents, nevertheless
leads towards a similar construction, and maybe as difficult
to account for. This specimen also much resembles the
Carbonate of Lime, represented at tab. 144. It is yet the
more extraordinary, as it is a large separated almost insulated
stone lying on the surface of a field at Scorrier-Housc, be-
longing to our kind friend Mr. Williams, where it is only
known, and to whose friendship I am indebted for the spe-
cimen showing the crimson, amethystine or pinkish Quartz.
With the other specimen I was favoured by Phil. Rashleigh,
CS q. — It is somewhat imitative of some of the Haematitic
Iron Ores, which have many centres, and radii of different
lengths. See tab. 133.

* Which will be figured ere long in Exotic Mineralogy.

VOL.CV.

1^

I

MS

171

TAB. CCCXCIV.

SI LEX Mica.
Silvery Mica.

I n the description of tab. 80, we noticed the difficulty of
imitating the lustre of this substance; but having found
means of partly surmounting that difficulty, we are happy
to produce examples in the present figure. This one is a
curious aggregation of laminated crystals, if I may so call
them. It is also very remarkable for being one of the first
examples of Mica showing an inclination to mackle. In
the present instance the plates are chiefly aggregates of
smaller rhomboidal ones; the mackle forms by the sides
of the rhombs being contrary to each other, like some of the
Gypsums. See the lower figure of tab. 223, which seems to
depend upon similar laws of -crystallization.

This is sometimes found in very large masses. I have
specimens six inches long from Aberdeen. — Schorle is oc-
casionally included in it.

I have lenticular crystals of this substance in an ordinary
specimen, which, as they certainly are but little if at all
noticed, I mention here. They are seemingly formed of
the laminae placed a little irregularly edgewise, resembling
the lenticular Sulphate of Barytes and some specimens of
Talc, which latter is however generally smaller, see tab. 182,
where they nearly approach this figure, or rather in tab. 74,
under the name Chlorite : see description, p. 154. I do not

doubt, now that it is observed, but that it will be found not
unfrequently. The specimen was sent me as gathered near
Aberdeen by a dealer without any particular observation,
but I could not let it escape unnoticed here. The specimen
on the whole is rather dull reddish brown.

TAB. CCCXCV.
Golden Mica.

This is a group of almost hexaedral laminae, but very
confused, and as it were compressed with layers of Sandy
Ouartz, &c. intervening. Its lustre is often so truly me-
tallic that it is like thin plates or squamae of Gold, nor could
wc represent it without metallic aid. — It is perhaps chiefly
coloured by Iron Ochre.

This specimen was brought from Aberdeen, and partakes
somewhat of the nature of Gneiss.

I

mm

kA5

TAB. CCCXCVL

ZINC V M sulphureuni.
Sulphuret of Zinc

Div.\. Crystallized. Far. Dodecaedral.

This substance has so many appearances, that it is of con-
sequence to identify some^ even of the ruder-looking ones,
which, after the neat examples figured in tabs. 74 and 75,
are hardly to be recognised as belonging to the same sub-
stance. The present, however, is not an unusual appearance
of some of the massy varieties, and is representative of the
primitive rhomboidal dodecaedron, and the same as the
fractured nucleus. It is altogether such a heap of small
indistinct appearances, that one can scarcely recognise
the parts showing what forms it belongs to ; nevertheless
with a little attention rugged dodecaedrons may be ob-
served. It exercises the early mineralogist in the study,
and stands with the more experienced as an instructive
lesson in 'the variations of Nature's school, always to be
esteemed for characteristics descriptive of herself. This and
the following figures serve to show the principal varieties of
crystallization, which continually form more or less com-
pounded forms and groups, that will occasionally combine
80 many modifications in one, that it is very difficult to
comprehend them.

There are some varieties in colour (as may be seen in a
slight decree), such as a fine orange brown and yellow, trans-
parent and brilliant, but generally in small crystals. It is
the resinous variety that is phosphorescent, or gives light
when scraped in the dark, some say with a brass pin ; but
I have some by favour of Mr. Pennant, from Flintshire, that
is so when scraped with a knife.

This ore is often used to procure the metal from.

TAB. CCCXCVIL

I^lack Jack, as this substance is commonly called by the
miners, is exemplified in this specimen with the usual ap-
pearance, and is indeed black to a proverb, for I know of
no substance that has a blacker aspect. Coal is perhaps
even blacker when powdered, in which state Jet is brown;
but this, which is full as dense and brilliant in the mass,

17

scrapes nearly to white dust, viz. light yellowish brown, not
much unlike rosin, which gives a whitish dust. The splen-
dent black crystals are generally grouped as well as con-
fusedly crystallized, showing their brilliant polished facets
one at a time occasionally very distinctly, but in the group
are merely jumbled masses. As they often form among
white Quartz, they are the more richly relieved ; and the
present specimen is additionally so, by the peculiarity of
some of the Quartz, which is found to be, when examined,
beautifully crystallized in relieved six-sided crystals, termi-
nated at each end by six-sided pyramids, but they are again
covered by an opaque, very white, almost mealy coat ; or
perhaps, having been acted ujion externally, have become
opaque by a division of the particles, which on that account
are so separable as to be scraped with a steel blade of a knife.
Specimens with a thin coat of Chalcedony next to the
Blende, and transparent Quartz above it, are less rare.

TAB. CCCXCVJII.

The various circumstances which attend a mineral are very
convenient to be known: I therefore have figured Sulphuret
of Zinc in one of its usual scattered appearances, and with
the seeming irregular crystallization common to it. Tt is
in tetraedrons, nearly as the geometrical figure of tab. 74,
more or less formed of smaller crystals with little shining
facets, or very dull, very different from those fine smooth
almost steel-like polished crystals in tab. 397.

I chose the present specimen, as it would elucidate some
other subjects if attentively considered. The matrix is
chiefly Quartz, which has probably formed over Cubic
Fluor, in a very loose and rough manner, as may be seen
by the impression ; and after the Fluor was gone, Galaena
or Sulphuret of Lead has formed in a scattered manner about
it. This Galaena has, however, mostly passed away, and left
Brown Pearlspar in thin walls, which, having covered the
cubes, are at right angles in the various positions in which
the Galaena originally lay.

Thus may be seen the changes wrought underground by
means of various agents; and thus we have continual proofs
of chemical agency, which perhaps may lead us to inqui-
ries that may be of considerable importance, while the sub-
ject thus come to hand is an example too curious to be
passed over at a time when investigations drawn from Na-
ture are found to be the truest mode of inquiry and im-
provement.

175

TAB. CCCXCIX.

PLUMBUM carbono-muriatum.
Carbono-muriatc of Lead.

Class. 3. Metals. Ord.

Gen. Lead. Spec. Carbono-muriate.

Syn. A New Variety of Lead Ore. Chenevix in Ni-
cholsons 4to Journal. 4. 219. Klaproth's Ana-
lyses, vol. 3.

I feel highly gratified in tjie opportunity of elucidating this
rare, substance, which does not seem to have been known to
be found, excepting in this country in the neighbourhood of
Cromford Level, near Matlock, Derbyshire. It was first
discovered to be a new mineral by the discerning Couni cle
Bournon, who has a primitive crystal of it, and many excel-
lent sketches and memorandums made tr 4 om our late good
friend the Hon. Charles Creville's superb collection, which
is now happily secured to this country in the British Mu-
seum, and from which we have selected the best specimens
for these figures.

The crystal is a rectangular prism, whose planes are pa-
rallel to the nucleus, sometimes having a cubical proportion,
with the angles replaced by isosceles triangular planes, the
incidence of which upon the terminal face is 122°. See Ike
llueish figures on the left of the yellow crystal, which look
like regular cubo-octaedrons. In these the columnar edges
are a little rounded by small faces, which in some crystals
are so much enlarged as almost to obliterate the primitive
ones. The yellowish lengthened crystal has the first of
these faces enlarged so as to form a four-sided pyramid,
with only a minute vestige of the terminal primitive plane,
and the edges of the prism replaced by truncating planes
arger than the portion they leave of the original faces.

This substance has generally a x glassy or gem-like lustre,,

IS

U. 1

176

1

is softer than Carbonate of Lead, which will scratch it, and
with which it has been confounded. It is accompanied by
small crystals of dull purplish Cubic Fluor, nearly in form
of a line above them ; and Galaena or Sulphuret of Lead on
the right, and which is distinguished bv its square appear-
ance. The whole on opaque Sulphate of Barytes, commonly
called Cawk in Derbyshire ; and there are some small cry-
stals of Carbonate of Lead scattered about it.

According to Mr. Greville, it was about the year 1785
that this curious local substance was found ; and the works
being discontinued, there are very few specimens known.
The outline or geometrical figure explains the form of the
columnar crystal, and agrees nearly with some other spe-
cimens which terminate with a flat apex.

H

1

TAB. CCCC.

This figure is taken from another crystal in the same col-
lection as the last. It is a short prism, and shows the pri-
mitive faces bv the parallelism of the conspicuous flaws or
fractures. It has also two additional faces on the columnar
edges, at 153° 30' with the primitive.

One of the specimens in the same collection has very thin
tabular crystals similarly modified, set edgewise, and form-
ing a group about three quarters of an inch in diameter.

The geometrical figure shows them with a more length-
ened column, forming sixteen columnar faces, besides the
eight faces which belong to the octaedron of the whole,
with the two ends being regular, and forming a polyedron of
26 faces : there are two of the truncated cubical crystals ac-
companying this.

Analysis by Chenevix.

Muriatic Acid . 8
Carbonic Acid . 6
Oxide of Lead . 85

99

ith

By Klaprovlu

. . . 8*50
little water 6*
. . , 85-50

too- 00

Spec. Grav. 60* 651 .

ALPHABETICAL INDEX.

TO

VOL. IV.

Actinolite, Brush-like

Alluvial depositions, forming soils .

Antimoine sulfure

Antimonium sulphureum

Antimony^ sulphurated

— — — sulphuret of

Argent natif octaedre

Argentum nativum cryst

Argile schisteuse

novaculaire . .

Argilla electrica

Topazius

Argillaceous Slate

Argillite

Argillo-Calcite

Axinite

B

Barytes sulphata

Sulphate of

— 1 — stalactitical x .

Bell-Metal ore

Bismuth, Carbonate of

natif

■ native • .

Bitumen, Inspissated

Bituminous Schistus

Blend, dodecaedral

. Borax gemma nobilis, Topazius
Braunspath

C

Calcareous Schist

Calcedony, Bony

VOL. IV. p

Tab.

Page.

379

149

335

61

123

365

ib.

ib.

365

ib.

45

327

ib.

97

355

101

331.378.389

53.147,163

363

117

353

97

ib.

ib.

41

31

380,381,382

151

380

ib.

381,382

153

67

344

77

75

343

ib.

361

113

17

396

175

117

34

347

85

J 3

175

ALPHABETICAL INDEX.

Calcedony, Cubic

■ Octaedra]

Shell- formed

Stalactitical

Calx carbonata

cryst

■ dodecaedra

, , metastatica . .

, fibrosa

magnesiata

Fluor, var. arenacea

phosphata

Carbo bituminosus

• vegeto-bituminosus

Chaux carbonated analogique

• contracr.ee

— — incrustante . .

, ,. prismatique

Chlorite Marie . .

Coal, bituminous, containing animal

^ remains

Kimmeridge

— plant-formed

Staffordshire

■ ■ ■ vegetable

Cobalt, Arseniateof

Flowers of

ore, black

• — oxide of

native >

oxyde noir $

Cobaltum arseniatum

■ oxygenizatum t

Cockle

Conchyliolithus productus

Copper, arseniate of, rotate

« hydrate of

Moss

native, wire-like

ore, black

* g; a y

■- vitreous . .

— — . peroxide of

• Pyrites Swimming . .

Subsulphuret of

Sulphate of

Tab.

Page.

308

12

307

1 1

310

14

309

13

317.323.34(3

25.37 83.85

1347.369,370

129J31

305,300.3 J 6

9,10.23

322

35

314,315

19

345

81

321

33

330

51

37'2

135

329.385,386

49.157

313

17

23

131

cq
00

O

324

39

386

150

313

17

385

157
»

320

40

313

17

326

43

ib.

' 69

340

ib.

ib.

326

43

340

69

147

21

303,304

5

302

3

144

376

143

111

107

359,360

109

302

3

301

1

359,360

109

351

9*

ALPHABETICAL INDEX.

Copper, Sulphuret of

Vitriol of

gray

Co rn a - a m n i o nis, Ca 1 cedon i zed

Cot ham Marble

Cuivre sulfate

« snlfure

gns

Cuprum arseniatum

• hyperoxygenizatum

— nativum

sulphatum

sulphureum

E

Etain oxyde concretionne ,
« ■ sulfure

F

Fahlerz >

Fahlore S " "
Ferram oxygenizatum

■ quartzosum . .

■ sulphatum . .

■ > sulphureum . .

Flints, Striped

Galaena, compact

— Mickensides

Garnet

■ Trapezoidal . .
Vesuvian

Granat, Edler

Granite

C r !u-spiess glanzerz

Green tone

Grenat granuliforme de Boheme

Growan

Grunstein

lab.

Page.

30

1 1

> 351

3 107

93

3K

) 14

32*

> 41

93

109

107

303,304

5

302

3

3/6

143

351

93

301

1

358,359,360

IO/.IO9.III

95

358

107

o / 5

141

J 27

000,60/ . 3/4

125.139.155

QQO O C A

ooo

iOJ>

392

167

ib.

121

373

137

371

133

121

332

55

122

47

121

68

47

130

ALPHABETICAL INDEX.

H

Hone-stone
Hornblend

common . .

Hornblende, gemeiner
Hornstone, Cubic
Hyacinthe, var.
Hydrogen Bitumen . .

Idocrase

Iron, oxide of * .

■ stone, Siliceous

sulphate of

sulphuret of . .

K

Killas . .
Kimmeridge Coal
Kupfer glanz . .
" schwartze

Labrador Stone, Scotch

Lapis ollaris

Lead, Carbonate of, in hexaedral la

minae

— Carbono muriate of, twisted . .

• , cubic

« Glance, spicular compact

' Green ores of

Sulphate of

Tab.

Page.

355

101

328

47

ib.

ib.

12

133

361

11S

371

133

375

141

368

127

350

91

366,367-383

125. 15S

384

65

313

Lime, Carbonate of

formed

columns

Columnar garnet-
• cryst. in hexaedral

Iroa

■ dodecaedral

■ Fibrous

. Incrusting

. Magnesian, with

348

342

399
400

341
316,317.369
370

318

305,306
322
345
346

321

17
109
111

57
87

73
179

181
167

71
ib.
23.129

27

9
35
81
83

32

ALPHABETICAL INDEX.

181

Lime, Carbonate of, metastatic

mackled

• Fluate of, arenaceous k . .

Phosphate of

Stone, Coralloid

M

Mica, Brown and black

■ Golden

Silvery

Moulds

Mytilus crassus

■ tunicatus

N

Novaculite

O

Opal

Osteocolla

P

Pechstein

Petrosilex resinite

Pierre de Thum 1

Pitchstone, Glassy

Porphyry

— Steatitic

Plomb sulfure compacte

Plumbum carbonatum

carbono-muriatum . .

« ■ sulpbamm

1 sulphureum

Potstone

Schistose

Pyrites, Cock's-comb

Curving or Bending

Swimming

Pyrope

Q

Quartz agathe

Crystallized

Fibrous. . .

Radiating or Stellated . .

Tab.

314
315
330
372
323

391

3Q5
3Q4
336
386
323

355

377
346

356

357

342
399,400
341
392
348

367
374
301

364

318
387
313

182

ALPHABETICAL INDEX.

R

Roche Feldspathique

Rotten-wood Rock

S

Sand, Silicious . ,

Sargestum

Schiller-spath

stone

Schist, Calcareous

^ Silicious

Schistus

Bituminous

Schorl, Curved

Pointed

Transparent lenticulaire

Violet

White

Schwarzer erdkobolt

Sidero Calcite

Sienite

Silex axinimorphum

fragilis

— granatum

— idocrasis

Mica . .

piceus

quartzum

** arenaceum

cry st.

— var

fibrosum . .

*~ , , opalinnra

stalactites . .

— stellatum . .

• Talcum

Silver, Crystallized native

Slate, Clay

Common argillaceous

Slickensides

Snake-stone

Soils

Spath Chatoyant

Stannum oxygen izatum

Tab.

Page.

332

55

102

362

115

126

59

334

ib.

347

85

355

101

97

17

390

164

389

163

31

ib.

331

53

69

33

333

57

320

31

379

149

364.373

121.137

371

133

391.394,395

165.171

356

103

307,308.388

1J, 12.162

362

115

318

27

310

14

387

161

377

145

309

13

393

I69

348

87

327

45

97

ib.

392

I67

354

99

335

61

5 9

337,338

6$

ALPHABETICAL INDEX.

Stannum oxygenizatum fibrosum
• sulpbureum

Strontia sulphata
Strontian, sulphate of, Brush-like '

radiated

. , stellated

T

Talc, Massive . .

Ollaire . .

Tar, Mineral

« Mountain

Thumerstein, Le
Thumerstone
Tin, Grain

ore, Wood . .

Oxide of . .

— — — haematitic

Pyrites

Shoad

Stone, Fibrous . .

Stream

— Sulphuret of

Wood

Topaz

occidental . .

Topaze

Topfstein

Tourmaline, Stellated
White . .

Vegetable Coal
Vismuthum nativum
Vismutum carbonatum

« nativum

Vitriol, Blue ..

W

Whet-slate . .
Wismuth, Gediegen. .

Tab.

Page.

352

339

67

311,312.319

15.29

312

16

311

15

311.319

15.29

67

ID.

113

ib.

id.

ID.

66

352

95

05

352

95

339

67

UU

y°

\J\J

^30

fi*7

352

95

363

117

ib.

ib.

O/

378

147

331

53

313

37

75

344

77

343

75

1 101

75

184

ALPHABETICAL INDEX.

Tab.

Page.

Y

Yanolithe

Z

Zinc, Sulphate of
Sulphuret of

349

396,397,398

89
175

89
ib.

J 73
07

Vitriol of. .

Zincum sulpha turn

sulphureum

Zinnkiess

349

396,397,398

CORRIGENDA.

Page. line.

12 10 for mamillated, read mammillated.

17 2 for Carbon, read Carbo.

22 penult, for pith, read pitch.

82 ult. for Rashley, read Rashleigh.

56 5 & 6 from the bottom, for "myself, by favour of Mr. W. Morel, being

detached," read tC my specimen by favour of W. Morel, Esq. was
detached."

63 12 for siliceous, read silicious.

6 ( J 2 for oxygenatum, oxygenizatum.

108 ] for tetrahedron, read tetraedron.

Ill 6 for hexangular, read hexaedral.

— - 25 for sulphuretted, read sulphureted.

118 4 & 5 ftom the bottom, dele the parenthesei.

121 12 for dingey, read dingy.

1 27 3 for siliceous, read silicious.

2 for Silex ctectricus, read Argilla electrica.

Printed by Richard Taylor and Co., Sh<>e Lane, London,